Auto merge of #15847 - shinglyu:treeherder-cleanup, r=Wafflespeanut

Remove link to servo from treeherder job detail to reduce noise

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(This PR was original created by wlach in the deprecated servo-perf repo: shinglyu/servo-perf#27)

Quoting his original message:
> The servo repository is already linked to from the revision list, there is no need for each job to link to it as well.
>This came up in: https://bugzilla.mozilla.org/show_bug.cgi?id=1342296

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [x] These changes do not require tests because need full treeherder setup to test

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etc/ci/performance/submit_to_perfherder.py

@@ -288,12 +288,6 @@ def submit(perf_data, failures, revision, summary, engine):
                         # 'job_guid': job_guid,
                         "blob": {
                             "job_details": [
-                                {
-                                    "content_type": "link",
-                                    "url": "https://www.github.com/servo/servo",
-                                    "value": "GitHub",
-                                    "title": "Source code"
-                                },
                                 {
                                     "content_type": "raw_html",
                                     "title": "Result Summary",