sap_install_media_detect: Fix linting errors

[marcelmamula]

Fixes for ansible-lint that is updated as part of #1118

Changes

• # noqa var-naming[no-role-prefix] added to all tasks setting other sap_install variables, because using .ansible-lint-ignore will show it as warnings, polluting log.
• Replace all detect_ register variables with correct internal name __sap_install_media_detect_register_

Result

ansible-lint --version
ansible-lint 25.9.0 using ansible-core:2.19.2 ansible-compat:25.8.1 ruamel-yaml:0.18.14 ruamel-yaml-clib:0.2.12

ansible-lint roles/sap_install_media_detect/

# Before
Failed: 73 failure(s), 0 warning(s) in 22 files processed of 24 encountered.

# After
Passed: 0 failure(s), 0 warning(s) in 22 files processed of 24 encountered.

[berndfinger]

LGTM