Merge `RUN` commands, remove unnecessary `grep` commands, remove redundancy.

[Montana]

• Merged multiple RUN commands where possible to reduce the number of layers.

• Removed unnecessary grep commands and simplified the disabling of protected mode.

• Removed redundant cd commands by combining them with the subsequent commands.

• Simplified the find and chown commands in the entrypoint script.

• Removed the echo $savedAptMark command as it doesn't serve a meaningful purpose.