[RabbitMQ] Add support for new timestamp format

[ritalwar]

• Enhancement

What does this PR do?

This PR supports RabbitMQ new timestamp format with nanosecond precision and timezone "2022-03-23 13:16:58.000369+03:00".
Previous timestamp format "2019-04-12 10:11:15.094".
New DATETIME pattern is replaced by TIMESTAMP_ISO8601.

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.

Related issues

• Relates Add support of a new RabbitMQ timestamp format #2905

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• Start Time: 2023-01-24T12:48:54.673+0000

• Duration: 13 min 7 sec

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Test	Results
Failed	0
Passed	17
Skipped	0
Total	17

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (1/1)	💚
Files	100.0% (1/1)	💚 2.295
Classes	100.0% (1/1)	💚 2.295
Methods	70.0% (14/20)	👎 -21.454
Lines	73.913% (34/46)	👎 -18.967
Conditionals	100.0% (0/0)	💚

[lalit-satapathy]

LGTM

[elasticmachine]

Package rabbitmq - 1.5.0 containing this change is available at https://epr.elastic.co/search?package=rabbitmq