Remove mta related workflow and targets

[bonzofenix]

Removes all MTA (Multi-Target Application) related deployment and cleanup logic from acceptance test workflows
Workflow Changes

• Deleted .github/workflows/acceptance_tests_mta.yaml
• Deleted .github/workflows/acceptance_tests_mta_close.yaml
• Removed deploy_apps input parameter from .github/workflows/acceptance_tests_reusable.yaml
• Eliminated MTA deployment triggering logic from reusable workflow
• Deleted ci/autoscaler/scripts/undeploy-apps.sh
• Removed cleanup_apps function from ci/autoscaler/scripts/common.sh
• Eliminated MTA-specific conditional logic from ci/autoscaler/scripts/deploy-autoscaler.sh
• Removed MTA-specific ops files and variables from deployment scripts
• Removed mta-release and mta-build target from Makefile
• Unified deployment naming convention (no longer branching between MTA and non-MTA deployments)

[silvestre]

Remove them from https://github.com/cloudfoundry/community/blob/ef5d769980d94a6f0130d7ffde5a717b2e004cb2/orgs/branchprotection.yml#L218 first

[bonzofenix]

@silvestre this is merged now cloudfoundry/community#1365

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

the change requested on community repo is already merged