[Stack 8.19.20-SNAPSHOT] [oracle] Failing test daily: system test: (elastic-agent logs - memory) in oracle.memory

- Stack version: 8.19.20-SNAPSHOT
- Package: oracle
- Failing test: system test: (elastic-agent logs - memory)
- DataStream: memory
- Owners:
- @elastic/obs-infraobs-integrations

Failure:
```
test case failed: one or more errors found while examining elastic-agent.logs2147579581: [0] found error "Unit state changed sql/metrics-default-sql/metrics-oracle-57ff0886-f966-4071-9dcf-44b76d5385f3 (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/47075

Latest 5 failed builds:
- https://buildkite.com/elastic/integrations/builds/48319
- https://buildkite.com/elastic/integrations/builds/48398
- https://buildkite.com/elastic/integrations/builds/48455
- https://buildkite.com/elastic/integrations/builds/48532
- https://buildkite.com/elastic/integrations/builds/48614

Start with the oracle.memory system test and inspect the elastic-agent logs and the linked Buildkite failures, focusing on the ORA-12541 no-listener error from sql.query. Done means the test no longer reports a degraded metrics-oracle unit or the connection failure in the latest builds.

Written by the indexing model from the issue text.