custom_profile_fields: Improve user validation efficiency.

[ngadou]

Refactor user validation in check_valid_user_ids function for custom profile fields in zerver/models/custom_profile_fields.py. Instead of individual queries within a loop to fetch user profiles, utilize a bulk fetch query with UserProfile.objects.filter() to retrieve user profiles efficiently. This change enhances performance, particularly for scenarios with multiple user IDs, ensuring a smoother user validation process.

The previous implementation iterated over each user ID to retrieve user profiles, resulting in potential performance overhead for large sets of user IDs. This refactor addresses the inefficiency by fetching user profiles in bulk, significantly reducing database queries and improving overall validation speed.

Fixes:
N/A

Screenshots and screen captures:
I am a new contributor and I am working on #29921 (PR #29977)

While Navigating the models, I fell on this note in the zerver/models/custom_profile_fields.py file

Self-review checklist

• Self-reviewed the changes for clarity and maintainability
  (variable names, code reuse, readability, etc.).

Communicate decisions, questions, and potential concerns.

• Explains differences from previous plans (e.g., issue description).
• Highlights technical choices and bugs encountered.
• Calls out remaining decisions and concerns.
• Automated tests verify logic where appropriate.

Individual commits are ready for review (see commit discipline).

• Each commit is a coherent idea.
• Commit message(s) explain reasoning and motivation for changes.

Completed manual review and testing of the following:

• Visual appearance of the changes.
• Responsiveness and internationalization.
• Strings and tooltips.
• End-to-end functionality of buttons, interactions and flows.
• Corner cases, error conditions, and easily imagined bugs.

[alya]

@timabbott Do you want to take a look at this directly?

[timabbott]

@ngadou did you intend to push changes in addition to marking my comment as resolved?

Check out our GitHub guide for advice on how to manage a PR.

[ngadou]

@ngadou did you intend to push changes in addition to marking my comment as resolved?

Check out our GitHub guide for advice on how to manage a PR.

Your feedback wasn't clear could you please state how the access_user_common instead of the is_bot

[timabbott]

What do you mean? git grep access_user_common.