Renamed docker startup scripts coherently.

[r-xyz]

Description

This PR renames all startup scripts for docker images coherently with 65ae03c.

No new features introduced.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• docker build

Test Configuration:

• PHP version: Docker
• MySQL version Docker
• Webserver version Docker
• OS version Docker

Checklist:

• I have read the Contributing documentation available here: https://snipe-it.readme.io/docs/contributing-overview
• I have formatted this PR according to the project guidelines: https://snipe-it.readme.io/docs/contributing-overview#pull-request-guidelines
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[what-the-diff]

PR Summary

This Pull Request makes updates to the Dockerfile configurations. Dockerfiles are scripts that contain collections of commands for constructing an image that can be used to deploy a container on the Docker platform.

• Updated Naming Conventions in Dockerfiles
  The main scripts that were earlier named as entrypoint_alpine.sh and docker-entrypoint.sh have been renamed to startup_alpine.sh and startup_alpine_fpm.sh respectively. This might make it more intuitive for users understanding the code.

• Changes in Docker Directives
  The 'command' (CMD) and 'entry point' (ENTRYPOINT) directives in the Dockerfiles are commands that are executed when a new container is created. We've changed these directives. In Dockerfile.alpine, the CMD directive has been switched from entrypoint.sh to startup.sh. Similarly, in Dockerfile.fpm-alpine, both ENTRYPOINT and CMD directives have been altered from docker-snipeit-entrypoint and docker-php-entrypoint to startup.sh.

These changes could make the startup processes within Docker containers more streamlined, thus enhancing overall docker container performance.

[uberbrady]

Nice cleanup! Thanks!