[zoom] Fix content-type handling

[marc-gr]

What does this PR do?

Adds config to ignore content-type checks.

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.

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Pinging @elastic/security-external-integrations (Team:Security-External Integrations)

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• Start Time: 2022-04-28T09:29:14.820+0000

• Duration: 15 min 30 sec

Test stats 🧪

Test	Results
Failed	0
Passed	13
Skipped	0
Total	13

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (1/1)	💚
Files	100.0% (10/10)	💚
Classes	100.0% (10/10)	💚
Methods	96.226% (51/53)	❕
Lines	89.889% (889/989)	❕
Conditionals	100.0% (0/0)	💚