chore: add test and docs for metrics

[xeniape]

Description

Part of stackabletech/issues#735
Trino already provides built-in Prometheus metrics per default. This PR adds testing the metrics endpoint and some documentation.

--- FAIL: kuttl (2045.00s)
    --- FAIL: kuttl/harness (0.00s)
        --- PASS: kuttl/harness/smoke_trino-451_hive-3.1.3_opa-1.4.2_hdfs-3.4.1_zookeeper-3.9.3_openshift-false (417.36s)
        --- PASS: kuttl/harness/smoke_trino-470_hive-4.0.1_opa-1.4.2_hdfs-3.4.1_zookeeper-3.9.3_openshift-false (435.47s)
        --- PASS: kuttl/harness/smoke_trino-476_hive-4.0.1_opa-1.4.2_hdfs-3.4.1_zookeeper-3.9.3_openshift-false (426.37s)
        --- FAIL: kuttl/harness/smoke_trino-476_hive-3.1.3_opa-1.4.2_hdfs-3.4.1_zookeeper-3.9.3_openshift-false (1182.69s)
        --- FAIL: kuttl/harness/smoke_trino-470_hive-3.1.3_opa-1.4.2_hdfs-3.4.1_zookeeper-3.9.3_openshift-false (1110.19s)
        --- PASS: kuttl/harness/smoke_trino-451_hive-4.0.1_opa-1.4.2_hdfs-3.4.1_zookeeper-3.9.3_openshift-false (426.83s)
FAIL
ERROR:root:kuttl failed

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    --- PASS: kuttl/harness (0.00s)
        --- PASS: kuttl/harness/smoke_trino-470_hive-3.1.3_opa-1.4.2_hdfs-3.4.1_zookeeper-3.9.3_openshift-false (409.48s)
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--- PASS: kuttl (373.74s)
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        --- PASS: kuttl/harness/smoke_trino-476_hive-3.1.3_opa-1.4.2_hdfs-3.4.1_zookeeper-3.9.3_openshift-false (373.73s)
PASS

Definition of Done Checklist

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Author

• Changes are OpenShift compatible
• CRD changes approved
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• Changes need to be "offline" compatible
• Links to generated (nightly) docs added
• Release note snippet added

Reviewer

• Code contains useful comments
• Code contains useful logging statements
• (Integration-)Test cases added
• Documentation added or updated. Follows the style guide.
• Changelog updated
• Cargo.toml only contains references to git tags (not specific commits or branches)

Acceptance

• Feature Tracker has been updated
• Proper release label has been added
• Links to generated (nightly) docs added
• Release note snippet added
• Add type/deprecation label & add to the deprecation schedule
• Add type/experimental label & add to the experimental features tracker

[razvan]

The AWS metrics test will not work like this but I'm personally also fine if you remove it.

[xeniape]

Metrics test was faulty and wasn't really testing anything. Fixed in b064649

--- PASS: kuttl (1198.39s)
    --- PASS: kuttl/harness (0.00s)
        --- PASS: kuttl/harness/smoke_trino-451_hive-3.1.3_opa-1.4.2_hdfs-3.4.1_zookeeper-3.9.3_openshift-false (374.15s)
        --- PASS: kuttl/harness/smoke_trino-470_hive-4.0.1_opa-1.4.2_hdfs-3.4.1_zookeeper-3.9.3_openshift-false (423.63s)
        --- PASS: kuttl/harness/smoke_trino-476_hive-4.0.1_opa-1.4.2_hdfs-3.4.1_zookeeper-3.9.3_openshift-false (377.99s)
        --- PASS: kuttl/harness/smoke_trino-476_hive-3.1.3_opa-1.4.2_hdfs-3.4.1_zookeeper-3.9.3_openshift-false (406.36s)
        --- PASS: kuttl/harness/smoke_trino-470_hive-3.1.3_opa-1.4.2_hdfs-3.4.1_zookeeper-3.9.3_openshift-false (445.70s)
        --- PASS: kuttl/harness/smoke_trino-451_hive-4.0.1_opa-1.4.2_hdfs-3.4.1_zookeeper-3.9.3_openshift-false (368.39s)
PASS

[razvan]

nice!