DBM statement_samples enabled by default, rename DBM-enabled key

[djova]

What does this PR do?

• statement_samples.enabled now defaults to true
• deep_database_monitoring renamed to dbm (while still supporting the old key)

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• PR title must be written as a CHANGELOG entry (see why)
• Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• PR must have changelog/ and integration/ labels attached

[codecov]

Codecov Report

Merging #9619 (80d3ad4) into master (7ea81df) will decrease coverage by 0.06%.
The diff coverage is 100.00%.

❗ Current head 80d3ad4 differs from pull request most recent head 7104133. Consider uploading reports for the commit 7104133 to get more accurate results
| Flag | Coverage Δ | |
|---|---|---|
| clickhouse | 96.95% <ø> (+0.40%) | ⬆️ |
| datadog_checks_base | 88.55% <ø> (-0.66%) | ⬇️ |
| elastic | 88.54% <ø> (ø) | |
| mysql | 85.76% <100.00%> (+1.10%) | ⬆️ |
| oracle | 93.58% <ø> (+1.23%) | ⬆️ |

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