Documentation/BreakingChanges: announce removal of git-pack-redundant(1)

The git-pack-redundant(1) command is already in the process of being
phased out and dies unless the user passes the `--i-still-use-this` flag
since 4406522b76 (pack-redundant: escalate deprecation warning to an
error, 2023-03-23). We haven't heard any complaints, so let's announce
the removal of this command in Git 3.0 in our breaking changes document.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/BreakingChanges.txt

@@ -115,6 +115,26 @@ info/grafts as outdated, 2014-03-05) and will be removed.
 +
 Cf. <20140304174806.GA11561@sigill.intra.peff.net>.
 
+* The git-pack-redundant(1) command can be used to remove redundant pack files.
+  The subcommand is unusably slow and the reason why nobody reports it as a
+  performance bug is suspected to be the absense of users. We have nominated
+  the command for removal and have started to emit a user-visible warning in
+  c3b58472be (pack-redundant: gauge the usage before proposing its removal,
+  2020-08-25) whenever the command is executed.
++
+So far there was a single complaint about somebody still using the command, but
+that complaint did not cause us to reverse course. On the contrary, we have
+doubled down on the deprecation and starting with 4406522b76 (pack-redundant:
+escalate deprecation warning to an error, 2023-03-23), the command dies unless
+the user passes the `--i-still-use-this` option.
++
+There have not been any subsequent complaints, so this command will finally be
+removed.
++
+Cf. <xmqq1rjuz6n3.fsf_-_@gitster.c.googlers.com>,
+    <CAKvOHKAFXQwt4D8yUCCkf_TQL79mYaJ=KAKhtpDNTvHJFuX1NA@mail.gmail.com>,
+    <20230323204047.GA9290@coredump.intra.peff.net>,
+
 == Superseded features that will not be deprecated
 
 Some features have gained newer replacements that aim to improve the design in