[azure] Ensure url.path cannot be duplicated

[dmathieu]

What does this PR do?

This is the same fix as in #5361, but for the url.path field.

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.

How to test this PR locally

Open the dev tools and run the following query to simulate a request:

POST _ingest/pipeline/logs-azure.application_gateway-1.5.25/_simulate
{
  "docs": [
    {
      "_source": {
        "json": {
          "properties": {
            "requestUri": "https://example.com"
          }
        },
        "url": {
          "path": "https://elastic.co"
        }
      }
    }
  ]
}

Related issues

Screenshots

[elasticmachine]

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Build stats

• Start Time: 2023-07-07T11:39:26.037+0000

• Duration: 14 min 16 sec

Test stats 🧪

Test	Results
Failed	0
Passed	83
Skipped	0
Total	83

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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)	👍 20.447
Lines	84.971% (2810/3307)	👎 -14.474
Conditionals	100.0% (0/0)	💚

[elasticmachine]

Package azure - 1.5.25 containing this change is available at https://epr.elastic.co/search?package=azure