[DBMON-5545] Update core tags with agent host name

[sangeetashivaji]

What does this PR do?

We want to add tags around agent hostname to be the tags.
Adding agent_hostname as the core tags to be able to inject it into the instance summary view, every query sample & into normalized queries

Testing:
Instance summary page:

Query Samples:

Normalized query:

Motivation

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

[sangeetashivaji]

this tags field is for custom tags and not for internal tags.
Adding agent_hostname as the core tags to be able to inject it into the instance summary view, every query sample & into normalized queries

Review from sethsamuel is dismissed. Related teams and files:

• database-monitoring-agent
  • mysql/tests/test_metadata.py
  • mysql/tests/test_mysql.py

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.50%. Comparing base (571da3a) to head (dbd93e2).
⚠️ Report is 69 commits behind head on master.

Additional details and impacted files

Flag	Coverage Δ
activemq	?
cassandra	?
confluent_platform	?
hive	?
hivemq	?
hudi	?
ignite	?
jboss_wildfly	?
kafka	?
presto	?
solr	?
tomcat	?
weblogic	?

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