Kerberos authentication failed

**Describe the bug**

Configure kerberos according to this documentation https://pulsar.apache.org/docs/en/security-kerberos/, throwing exceptions

```
Exception: javax.naming.AuthenticationException: SASL/JAAS errorjavax.security.sasl.SaslException: GSS initiate failed [Caused by GSSException: No valid credentials provided (Mechanism level: Server not found in Kerberos database (7) - LOOKING_UP_SERVER)]
org.apache.pulsar.client.admin.PulsarAdminException: java.util.concurrent.ExecutionException: org.apache.pulsar.client.admin.PulsarAdminException$GettingAuthenticationDataException: javax.naming.AuthenticationException: SASL/JAAS errorjavax.security.sasl.SaslException: GSS initiate failed [Caused by GSSException: No valid credentials provided (Mechanism level: Server not found in Kerberos database (7) - LOOKING_UP_SERVER)]
at org.apache.pulsar.client.admin.internal.BaseResource.getApiException(BaseResource.java:247) ~[org.apache.pulsar-pulsar-client-admin-original-2.8.1.jar:2.8.1]
at org.apache.pulsar.client.admin.internal.TenantsImpl$1.failed(TenantsImpl.java:72) ~[org.apache.pulsar-pulsar-client-admin-original-2.8.1.jar:2.8.1]
at org.apache.pulsar.client.admin.internal.BaseResource.asyncGetRequest(BaseResource.java:167) ~[org.apache.pulsar-pulsar-client-admin-original-2.8.1.jar:2.8.1]
at org.apache.pulsar.client.admin.internal.TenantsImpl.getTenantsAsync(TenantsImpl.java:63) ~[org.apache.pulsar-pulsar-client-admin-original-2.8.1.jar:2.8.1]
at org.apache.pulsar.client.admin.internal.TenantsImpl.getTenants(TenantsImpl.java:49) ~[org.apache.pulsar-pulsar-client-admin-original-2.8.1.jar:2.8.1]
at org.apache.pulsar.PulsarStandalone.createNameSpace(PulsarStandalone.java:361) [org.apache.pulsar-pulsar-broker-2.8.1.jar:2.8.1]
at org.apache.pulsar.PulsarStandalone.start(PulsarStandalone.java:349) [org.apache.pulsar-pulsar-broker-2.8.1.jar:2.8.1]
at org.apache.pulsar.PulsarStandaloneStarter.main(PulsarStandaloneStarter.java:121) [org.apache.pulsar-pulsar-broker-2.8.1.jar:2.8.1]
Caused by: java.util.concurrent.ExecutionException: org.apache.pulsar.client.admin.PulsarAdminException$GettingAuthenticationDataException: javax.naming.AuthenticationException: SASL/JAAS errorjavax.security.sasl.SaslException: GSS initiate failed [Caused by GSSException: No valid credentials provided (Mechanism level: Server not found in Kerberos database (7) - LOOKING_UP_SERVER)]
at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357) ~[?:1.8.0_292]
at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1908) ~[?:1.8.0_292]
at org.apache.pulsar.client.admin.internal.BaseResource.request(BaseResource.java:68) ~[org.apache.pulsar-pulsar-client-admin-original-2.8.1.jar:2.8.1]
at org.apache.pulsar.client.admin.internal.BaseResource.asyncGetRequest(BaseResource.java:165) ~[org.apache.pulsar-pulsar-client-admin-original-2.8.1.jar:2.8.1]
... 5 more
Caused by: org.apache.pulsar.client.admin.PulsarAdminException$GettingAuthenticationDataException: javax.naming.AuthenticationException: SASL/JAAS errorjavax.security.sasl.SaslException: GSS initiate failed [Caused by GSSException: No valid credentials provided (Mechanism level: Server not found in Kerberos database (7) - LOOKING_UP_SERVER)]
at org.apache.pulsar.client.admin.internal.BaseResource.requestAsync(BaseResource.java:111) ~[org.apache.pulsar-pulsar-client-admin-original-2.8.1.jar:2.8.1]
at org.apache.pulsar.client.admin.internal.BaseResource.request(BaseResource.java:68) ~[org.apache.pulsar-pulsar-client-admin-original-2.8.1.jar:2.8.1]
at org.apache.pulsar.client.admin.internal.BaseResource.asyncGetRequest(BaseResource.java:165) ~[org.apache.pulsar-pulsar-client-admin-original-2.8.1.jar:2.8.1]
... 5 more
Caused by: javax.naming.AuthenticationException: SASL/JAAS errorjavax.security.sasl.SaslException: GSS initiate failed [Caused by GSSException: No valid credentials provided (Mechanism level: Server not found in Kerberos database (7) - LOOKING_UP_SERVER)]
at org.apache.pulsar.client.impl.auth.PulsarSaslClient.evaluateChallenge(PulsarSaslClient.java:116) ~[org.apache.pulsar-pulsar-client-auth-sasl-2.8.1.jar:2.8.1]
at org.apache.pulsar.client.impl.auth.SaslAuthenticationDataProvider.authenticate(SaslAuthenticationDataProvider.java:55) ~[org.apache.pulsar-pulsar-client-auth-sasl-2.8.1.jar:2.8.1]
at org.apache.pulsar.client.impl.auth.AuthenticationSasl.newRequestHeader(AuthenticationSasl.java:264) ~[org.apache.pulsar-pulsar-client-auth-sasl-2.8.1.jar:2.8.1]
at org.apache.pulsar.client.impl.auth.AuthenticationSasl.newRequestBuilder(AuthenticationSasl.java:198) ~[org.apache.pulsar-pulsar-client-auth-sasl-2.8.1.jar:2.8.1]
at org.apache.pulsar.client.impl.auth.AuthenticationSasl.authenticationStage(AuthenticationSasl.java:307) ~[org.apache.pulsar-pulsar-client-auth-sasl-2.8.1.jar:2.8.1]
at org.apache.pulsar.client.admin.internal.BaseResource.requestAsync(BaseResource.java:82) ~[org.apache.pulsar-pulsar-client-admin-original-2.8.1.jar:2.8.1]
at org.apache.pulsar.client.admin.internal.BaseResource.request(BaseResource.java:68) ~[org.apache.pulsar-pulsar-client-admin-original-2.8.1.jar:2.8.1]
at org.apache.pulsar.client.admin.internal.BaseResource.asyncGetRequest(BaseResource.java:165) ~[org.apache.pulsar-pulsar-client-admin-original-2.8.1.jar:2.8.1]
... 5 more
```

**To Reproduce**
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4. See error

**Expected behavior**
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**Additional context**
Add any other context about the problem here.

Review the Kerberos configuration linked in the issue and start at PulsarSaslClient.evaluateChallenge, then follow the PulsarStandalone startup path shown in the stack trace. Establish a minimal reproducible configuration for the Server not found in Kerberos database error. Done means the reproduction is explained and admin authentication succeeds or the documented configuration is corrected.

Written by the indexing model from the issue text.