[8.x](backport #6380) test: increase passwd length in crypto io tests

[mergify]

What does this PR do?

the password is used to derive a key using pbkdf2 and hmac.

Update the test to use longer passwords.

Why is it important?

In fips only mode use of keys shorter than 112 bits is not allowed for hmac.

The program will panic with the following error:

panic: crypto/hmac: use of keys shorter than 112 bits is not allowed in FIPS 140-only mode

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in ./changelog/fragments using the changelog tool
• I have added an integration test or an E2E test

Disruptive User Impact

How to test this PR locally

Related issues

Questions to ask yourself

• How are we going to support this in production?
• How are we going to measure its adoption?
• How are we going to debug this?
• What are the metrics I should take care of?
• ...

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This is an automatic backport of pull request #6380 done by [Mergify](https://mergify.com).

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarQube