[LogsDB] [Stack 8.19.19-SNAPSHOT] [oracle] Failing test daily: system test: (elastic-agent logs - sysmetric) in oracle.sysmetric

- Stack version: 8.19.19-SNAPSHOT
- LogsDB: enabled
- Package: oracle
- Failing test: system test: (elastic-agent logs - sysmetric)
- DataStream: sysmetric
- Owners:
- @elastic/obs-infraobs-integrations

Failure:
```
test case failed: one or more errors found while examining elastic-agent.logs2138423984: [0] found error "Unit state changed sql/metrics-default-sql/metrics-oracle-c5685e73-94a5-4864-9f47-c108672903c1 (HEALTHY->DEGRADED): Error fetching data for metricset sql.query: cannot open connection: testing connection: user=\"sys\" standalone params={authMode:2 connectionClass: connectionClassLength:0 purity:0 newPassword: newPasswordLength:0 appContext: numAppContext:0 externalAuth:0 externalHandle: pool: tag: tagLength:0 matchAnyTag:0 outTag: outTagLength:0 outTagFound:0 shardingKeyColumns: numShardingKeyColumns:0 superShardingKeyColumns: numSuperShardingKeyColumns:0 outNewSession:0}: ORA-12541: TNS:no listener"
```

First build failed: https://buildkite.com/elastic/integrations/builds/46082

Latest 5 failed builds:
- https://buildkite.com/elastic/integrations/builds/46709
- https://buildkite.com/elastic/integrations/builds/46802
- https://buildkite.com/elastic/integrations/builds/46860
- https://buildkite.com/elastic/integrations/builds/46919
- https://buildkite.com/elastic/integrations/builds/47004

Start with the failing Oracle sysmetric system test and compare the first failed build with the five later Buildkite failures. Investigate the ORA-12541 no-listener error and the test environment's Oracle connection setup; done means the test passes reliably in the integrations builds.

Written by the indexing model from the issue text.