Fix version collection

[FlorianVeaux]

Apache version can be collected from three places:

• from the mod_status html output
• from the mod_status machine-readable output
• or from the 'Status' header in any request to Apache.

A few notes:

• The check does not expect an html output.
• The machine-readable output only contains the version since version 2.4.20
• The status header does not always contain the full version (it can be hidden using server configuration parameters).

This PR first fixes the behavior of the _collect_metadata method to prevent failing.
It also tries to extract the version from the machine-readable output before falling back to the 'Status' header

[codecov]

Codecov Report

Merging #5252 into master will increase coverage by 3.66%.
The diff coverage is 88.88%.

Impacted Files	Coverage Δ
apache/tests/test_apache.py	86.53% <100%> (+2.44%)	⬆️
apache/tests/conftest.py	100% <100%> (ø)	⬆️
apache/datadog_checks/apache/apache.py	89.04% <76.47%> (-2.9%)	⬇️
vertica/tests/metrics.py
clickhouse/datadog_checks/clickhouse/utils.py
...checks_dev/tests/plugin/test_environment_runner.py
riakcs/datadog_checks/riakcs/riakcs.py
oracle/tests/test_oracle.py
...r/datadog_checks/openstack_controller/__about__.py
twistlock/datadog_checks/twistlock/twistlock.py
... and 911 more

[therve]

Some minor comments, looks good otherwise.

[mattyo161]

@FlorianVeaux is it possible to patch this fix into the 6.16.x branch as well?

[FlorianVeaux]

@mattyo161 Yes working on it 👍