ccl/sqlproxyccl: TestProxyAgainstSecureCRDB failed

ccl/sqlproxyccl.TestProxyAgainstSecureCRDB [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Ci_TestsAwsLinuxArm64_UnitTests/19656477?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Ci_TestsAwsLinuxArm64_UnitTests/19656477?buildTab=artifacts#/) on release-25.2 @ [3b2df7cef4b9f75078a6133dc2b18f07dd0e1028](https://github.com/cockroachdb/cockroach/commits/3b2df7cef4b9f75078a6133dc2b18f07dd0e1028):

```
=== RUN TestProxyAgainstSecureCRDB
test_log_scope.go:165: test logs captured to: /artifacts/tmp/_tmp/9fd0ddd2a515e470896c2a13882e29c6/logTestProxyAgainstSecureCRDB921456725
test_log_scope.go:76: use -show-logs to present logs inline
test_server_shim.go:154: automatically injected an external process virtual cluster under test; see comment at top of test_server_shim.go for details.
proxy_handler_test.go:858: -- test log scope end --
test logs left over in: /artifacts/tmp/_tmp/9fd0ddd2a515e470896c2a13882e29c6/logTestProxyAgainstSecureCRDB921456725
--- FAIL: TestProxyAgainstSecureCRDB (3.23s)
=== RUN TestProxyAgainstSecureCRDB/SNI_and_database_provided_but_SNI_ignored
proxy_handler_test.go:2918:
Error Trace: pkg/ccl/sqlproxyccl/proxy_handler_test.go:2945
Error: Expected nil, but got: &sqlproxyccl.errWithCode{
code: 4,
cause: &withstack.withStack{
cause: &errutil.withPrefix{
cause: &errors.errorString{s:"invalid length of startup packet: 369295617"},
prefix: "while receiving startup message",
},
stack: &withstack.stack{0x46a26d1, 0x46af1fc, 0x46b4d60, 0x184b888, 0x4934d4},
},
}
Test: TestProxyAgainstSecureCRDB/SNI_and_database_provided_but_SNI_ignored
--- FAIL: TestProxyAgainstSecureCRDB/SNI_and_database_provided_but_SNI_ignored (0.09s)
```
Help

See also: [How To Investigate a Go Test Failure \(internal\)](https://cockroachlabs.atlassian.net/l/c/HgfXfJgM)

Same failure on other branches

- #144263 ccl/sqlproxyccl: TestProxyAgainstSecureCRDB failed [C-test-failure O-robot T-serverless branch-master release-blocker]

/cc @cockroachdb/sql-foundations @cockroachdb/server

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Jira issue: CRDB-50531