Remove avatar markdown

[vtyagi26]

This is PR related to issue #649 wherein I changed the occurence of !avatar syntax from /zulip/integration/git.

Fixes: I changed the occurence of this syntax from 2 files :

1. zulip_git_config.py -> line 41
2. post-receive -> line 50

How did you test this PR?
After successfully removing the !avatar syntax from these locations i ran a commit message locally with dummy entries and found that everything is working fine.

Self-review checklist

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

What do you mean that it's related? Should it be reviewed after the other one is merged? Or should the changes here be pushed to the PR you already have open?

[vtyagi26]

This is PR related to issue #649 wherein I changed the occurence of !avatar syntax from /zulip/integration/git.

Fixes: I changed the occurence of this syntax from 2 files :

1. zulip_git_config.py -> line 41
2. post-receive -> line 50

How did you test this PR? After successfully removing the !avatar syntax from these locations i ran a commit message locally with dummy entries and found that everything is working fine.

Self-review checklist

What do you mean that it's related? Should it be reviewed after the other one is merged? Or should the changes here be pushed to the PR you already have open?

What i mean is the current PR passes 13/14 checks, the 1 check which is failing is not due to the code, its some unrelated issue so i am waiting for the review. sorry for any confusion.

[alya]

This PR makes over a million lines of changes, so I'll go ahead and close it out.

Please review the contributor guide to learn how to contribute to Zulip, and avoid wasting maintainer time.