[AWS] Add the ignore_missing and null checks to rename processor

[ishleenk17]

• Bug

What does this PR do?

This PR adds the if check for event.original and the ignore_missing check for the renaming of message to event.original

Most of the AWS packages have already taken care of this check.
Some of the packages missing these have been addressed here:

• cloudwatch_logs
• gaurduty
• inspector
• securityhub_findings
• securityhub_insights

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 checks to rename processor for the message field for all Observability Integrations #7822

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• Start Time: 2023-10-10T05:22:56.888+0000

• Duration: 56 min 43 sec

Test stats 🧪

Test	Results
Failed	0
Passed	212
Skipped	3
Total	215

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (17/17)	💚
Files	94.444% (17/18)	👎 -2.243
Classes	94.444% (17/18)	👎 -2.243
Methods	86.047% (259/301)	👎 -6.315
Lines	86.083% (7571/8795)	👎 -2.331
Conditionals	100.0% (0/0)	💚

[elasticmachine]

Package aws - 2.8.2 containing this change is available at https://epr.elastic.co/search?package=aws