[META] Ensure changes to admin credentials work on all supported OpenSearch distributions

[DarshitChanpura]

High-level Idea

Stemming from the spike, this feature-requests focuses on ensuring all distributions work as expected once the hardcoded admin password has been replace with a more dynamic value.
This issue should be worked in tandem with the meta to update the code to replace hardcoded admin password inside demo configuration script.

Acceptance Criteria

• The modification is implemented in all compatible OpenSearch distributions.
• The change is reflected consistently across all supported OpenSearch distributions.

Exit Criteria

• Docker distribution should reflect changes to default admin credentials in demo configuration #3705
• Ensure admin password changes work with TAR distribution #3634
• ZIP distribution should reflect changes to default admin credentials in demo configuration #3708
• RPM distribution should reflect changes to default admin credentials in demo configuration #3709
• DEB distribution should reflect changes to default admin credentials in demo configuration #3710
• HELM charts distribution should reflect changes to default admin credentials in demo configuration #3711
• Ansible distribution should reflect changes to default admin credentials in demo configuration #3712

[stephen-crawford]

[Triage] This is another meta issue related to the work of removing the use of default credentials. Marking as triaged given clear exit criteria and action items.

[derek-ho]

There are three test cases for each distribution type that needs to be verified:

1. Run without initialAdminPassword environment variable set, no initialAdminPassword.txt.
   a. Verify a secure password is generated
   b. Verify that admin:admin fails authentication
   c. Verify that admin:${Generated Password} succeeds authentication
2. Run with initialAdminPassword environment variable set
   a. Verify that a "weak" password fails and stops script execution in a clean way
   b. Verify that a "strong" password succeeds
   i. Verify that admin:admin fails authentication
   ii. Verify that admin:${initialAdminPassword} succeeds authentication
3. Run without initialAdminPassword environment variable set, initialAdminPassword.txt present.
   a. Verify that a "weak" password fails and stops script execution in a clean way
   b. Verify that a "strong" password succeeds
   i. Verify that admin:admin fails authentication
   ii. Verify that admin:${initialAdminPassword.txt contents} succeeds authentication

[DarshitChanpura]

acceptance criteria met. Refer each individual issues for more details.