[Azure Logs] Fix authentication_processing_details parsing in sign-in logs

[zmoog]

What does this PR do?

What

Replace the foreach + set processors combo with a single script processor in the ingest pipeline for Azure AD sign-in logs.

Why

The set processor expands the dots contained in the field name into subfields.

Sometimes attributes contained in authentication_processing_details have dots, for example:

# source
{"key": "a.b.c", "value": true}

In such cases, the set processor would turn it into:

# this is a side-effect
{
  "a": {
    "b": {
      "c": true
    }
  }
}

Instead of:

# this is the expected result
{"a.b.c": True}

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.

Author's Checklist

• [ ]

How to test this PR locally

Related issues

• Relates [Filebeat] Azure Signin Module authentication_processing_details Issue beats#34330

Screenshots

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• Start Time: 2023-02-07T13:56:57.456+0000

• Duration: 15 min 11 sec

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Failed	0
Passed	124
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Total	124

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (10/10)	💚
Files	86.364% (19/22)	👎 -13.636
Classes	86.364% (19/22)	👎 -13.636
Methods	83.333% (155/186)	👎 -16.667
Lines	85.047% (2787/3277)	👎 -7.26
Conditionals	100.0% (0/0)	💚

[UcanInfosec]

If ready, let’s move forward with this

[elasticmachine]

Package azure - 1.5.7 containing this change is available at https://epr.elastic.co/search?package=azure