revert(3p/git): Revert merge of git upstream at v2.26.2

This causes cgit to serve error pages, which is undesirable.

This reverts commit 5229c9b232, reversing
changes made to f2b211131f.

third_party/git/Documentation/config/fetch.txt

@@ -59,8 +59,7 @@ fetch.negotiationAlgorithm::
 	effort to converge faster, but may result in a larger-than-necessary
 	packfile; The default is "default" which instructs Git to use the default algorithm
 	that never skips commits (unless the server has acknowledged it or one
-	of its descendants). If `feature.experimental` is enabled, then this
-	setting defaults to "skipping".
+	of its descendants).
 	Unknown values will cause 'git fetch' to error out.
 +
 See also the `--negotiation-tip` option for linkgit:git-fetch[1].
@@ -69,23 +68,3 @@ fetch.showForcedUpdates::
 	Set to false to enable `--no-show-forced-updates` in
 	linkgit:git-fetch[1] and linkgit:git-pull[1] commands.
 	Defaults to true.
-
-fetch.parallel::
-	Specifies the maximal number of fetch operations to be run in parallel
-	at a time (submodules, or remotes when the `--multiple` option of
-	linkgit:git-fetch[1] is in effect).
-+
-A value of 0 will give some reasonable default. If unset, it defaults to 1.
-+
-For submodules, this setting can be overridden using the `submodule.fetchJobs`
-config setting.
-
-fetch.writeCommitGraph::
-	Set to true to write a commit-graph after every `git fetch` command
-	that downloads a pack-file from a remote. Using the `--split` option,
-	most executions will create a very small commit-graph file on top of
-	the existing commit-graph file(s). Occasionally, these files will
-	merge and the write may take longer. Having an updated commit-graph
-	file helps performance of many Git commands, including `git merge-base`,
-	`git push -f`, and `git log --graph`. Defaults to false, unless
-	`feature.experimental` is true.