[Bug]: [Docker] Security plugin demo config install script executes even if security plugin is disabled

[DarshitChanpura]

Describe the bug

The code in opensearch-docker-entrypoint.sh currently installs demo config first if enabled and then check whether security plugin is disabled. See here

To reproduce

Run:

docker pull opensearchstaging/opensearch:2.12.0.9399 && docker run -it -p 9200:9200 -e "DISABLE_SECURITY_PLUGIN=true" -e "discovery.type=single-node" opensearchstaging/opensearch:2.12.0.9399
2.12.0.9399: Pulling from opensearchstaging/opensearch

Expected behavior

Cluster should start without any errors related to security-plugin.

Screenshots

If applicable, add screenshots to help explain your problem.

Host / Environment

No response

Additional context

No response

Relevant log output

➜  ~ docker pull opensearchstaging/opensearch:2.12.0.9399 && docker run -it -p 9200:9200 -e "DISABLE_SECURITY_PLUGIN=true" -e "discovery.type=single-node" opensearchstaging/opensearch:2.12.0.9399
2.12.0.9399: Pulling from opensearchstaging/opensearch
Digest: sha256:87b2c2bed78237714aea05572b71757470b9b0622867615dde14c1ac3e2eeb27
Status: Image is up to date for opensearchstaging/opensearch:2.12.0.9399
docker.io/opensearchstaging/opensearch:2.12.0.9399

What's Next?
  1. Sign in to your Docker account → docker login
  2. View a summary of image vulnerabilities and recommendations → docker scout quickview opensearchstaging/opensearch:2.12.0.9399
Enabling execution of install_demo_configuration.sh for OpenSearch Security Plugin
OpenSearch 2.12.0 onwards, the OpenSearch Security Plugin a change that requires an initial password for 'admin' user.
Please define an environment variable 'OPENSEARCH_INITIAL_ADMIN_PASSWORD' with a strong password string.
If a password is not provided, the setup will quit.
 For more details, please visit: https://opensearch.org/docs/latest/install-and-configure/install-opensearch/docker/
### OpenSearch Security Demo Installer
### ** Warning: Do not use on production or public reachable systems **
OpenSearch install type: rpm/deb on Linux 6.6.12-linuxkit aarch64
OpenSearch config dir: /usr/share/opensearch/config/
OpenSearch config file: /usr/share/opensearch/config/opensearch.yml
OpenSearch bin dir: /usr/share/opensearch/bin/
OpenSearch plugins dir: /usr/share/opensearch/plugins/
OpenSearch lib dir: /usr/share/opensearch/lib/
Detected OpenSearch Version: 2.12.0
Detected OpenSearch Security Version: 2.12.0.0
No custom admin password found. Please provide a password via the environment variable OPENSEARCH_INITIAL_ADMIN_PASSWORD.
➜  ~

[rishabh6788]

Please update the README on the PR.

[DarshitChanpura]

done.