PostgreSQL: Create postgresql.create_index.* metrics tracking progress of index creation

[bonnefoa]

What does this PR do?

Add metrics based on pg_stat_progress_create_index

Motivation

We want to be able to track the state of index/reindex (how many tuples processed...) and if an index command is blocked.

Additional Notes

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Changelog entries must be created for modifications to shipped code
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.

[codecov]

Codecov Report

Merging #16330 (88c7374) into master (185df30) will decrease coverage by 4.07%.
The diff coverage is 100.00%.

❗ Current head 88c7374 differs from pull request most recent head 6c6bcf1. Consider uploading reports for the commit 6c6bcf1 to get more accurate results

Additional details and impacted files

Flag	Coverage Δ
activemq	?
cassandra	?
hive	?
hivemq	?
jboss_wildfly	?
postgres	92.29% <100.00%> (+0.04%)	⬆️
presto	?
solr	?
tomcat	?

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[github-actions]

Test Results

     16 files       16 suites   19m 51s ⏱️
   266 tests    264 ✔️     2 💤 0 ❌
2 136 runs  2 032 ✔️ 104 💤 0 ❌

Results for commit 6c6bcf1.

♻️ This comment has been updated with latest results.