Remove mention of now removed triagebot glacier integration

Author: fmease

src/SUMMARY.md

@@ -22,7 +22,6 @@
     - [Close](./triagebot/close.md)
     - [Documentation Updates](./triagebot/doc-updates.md)
     - [GitHub Releases](./triagebot/github-releases.md)
-    - [Glacier](./triagebot/glacier.md)
     - [Issue Links](./triagebot/issue-links.md)
     - [Issue Transfer](./triagebot/transfer.md)
     - [Labeling](./triagebot/labeling.md)