Add Oracle WebLogic 14.1.2 support

## Is your feature request related to a problem?

The [supported technologies matrix](https://www.elastic.co/docs/reference/apm/agents/java/supported-technologies) lists Oracle WebLogic 12.2 as the only version covered by the integration test suite. On **WebLogic 14.1.2.0.0** the agent cannot reach APM Server at all. Reverting back to 12c fixes the issue.

The agent starts and the tracer reaches `RUNNING`, then every outbound HTTP call fails because WebLogic's own HTTP client returns a null socket factory:

```
WARN co.elastic.apm.agent.report.ApmServerHealthChecker - Elastic APM server http://:8200/ is not available (Cannot invoke "javax.net.SocketFactory.createSocket()" because the return value of "weblogic.net.http.HttpClient.getSocketFactory()" is null)
java.lang.NullPointerException: Cannot invoke "javax.net.SocketFactory.createSocket()" because the return value of "weblogic.net.http.HttpClient.getSocketFactory()" is null
at weblogic.net.http.HttpClient.openServer(HttpClient.java:403) ~[com.oracle.weblogic.net.jar:14.1.2.0]
at weblogic.net.http.HttpClient.New(HttpClient.java:329) ~[com.oracle.weblogic.net.jar:14.1.2.0]
at weblogic.net.http.HttpURLConnection.connect(HttpURLConnection.java:368) ~[com.oracle.weblogic.net.jar:14.1.2.0]
at weblogic.net.http.HttpURLConnection.getInputStream(HttpURLConnection.java:770) ~[com.oracle.weblogic.net.jar:14.1.2.0]
at weblogic.net.http.SOAPHttpURLConnection.getInputStream(SOAPHttpURLConnection.java:42) ~[com.oracle.weblogic.net.jar:14.1.2.0]
at co.elastic.apm.agent.report.HttpUtils.consumeAndClose(HttpUtils.java:62) ~[elastic-apm-agent-1.56.0.jar:1.56.0]
at co.elastic.apm.agent.report.ApmServerClient.executeForAllUrls(ApmServerClient.java:306) ~[elastic-apm-agent-1.56.0.jar:1.56.0]
at co.elastic.apm.agent.report.ApmServerHealthChecker.call(ApmServerHealthChecker.java:67) ~[elastic-apm-agent-1.56.0.jar:1.56.0]
```

Two things distinguish this from prior reports:

- It occurs on **plain HTTP**, not HTTPS.
- It is a **different failure** from #2409, which was an HTTPS `ClassNotFoundException` for `weblogic.security.SSL.jsseadapter.JaSSLContextImpl`. That was fixed by #3870, and 1.56.0 includes the fix, so the socket factory returning `null` is not covered by it.

Remaining on 12.2 is not always an available option.

## Describe the solution you'd like

Add **Oracle WebLogic 14.1.2** to the tested matrix, so the agent connects to APM Server on that version without workarounds.

## Describe alternatives you've considered

- **`-DUseSunHttpHandler=true`** makes WebLogic defer to the JDK's Sun HTTP handler instead of its own, bypassing the failing class. Reported in earlier WebLogic cases as a global flag that also alters WebLogic's own HTTP behaviour, so a trade-off rather than a clean workaround. Untested against this failure.
- **`elastic.apm.delay_agent_premain_ms`** was tried during the earlier WebLogic investigation and did not reliably help there.
- **HTTPS rather than HTTP.** A distinct WebLogic code path, and the one agent-side defect known to affect it (#2409) is fixed in 1.56.0. Untested here, and gated on the deployment having TLS available.

## Additional context

Environment where this was reproduced:

| | |
|---|---|
| WebLogic | 14.1.2.0.0, production mode, managed server started via NodeManager |
| JDK | Oracle JDK 21 |
| Agent | 1.56.0 |
| APM Server | self-managed, plain HTTP |
| OS | Linux (RHEL 8) |

Start with the supported technologies matrix and the WebLogic HTTP failure described in the issue, comparing the existing 12.2 integration coverage with WebLogic 14.1.2. Reproduce against WebLogic 14.1.2.0.0, Oracle JDK 21, agent 1.56.0, and plain HTTP; done means the agent reaches APM Server without the null socket-factory failure and the version is covered by integration tests.

Written by the indexing model from the issue text.