[roll] Roll fuchsia [roll] Roll third_party/openthread [srp] Increase SRP service update timeout to 2500ms

Increase `OPENTHREAD_CONFIG_SRP_SERVER_SERVICE_UPDATE_TIMEOUT` from the
default 1250ms to 2500ms in `openthread-config-fuchsia.h`.

On Fuchsia, the SRP advertising proxy (`lowpan-ot-driver`) publishes the
proxy host and its service instances sequentially via `fuchsia.net.mdns`
rather than probing them in parallel. Each mDNS probe (`AddressProber`
for the host and `InstanceProber` for services) takes 750ms-1000ms (0 to
250ms initial random delay plus three 250ms probe intervals):

- Host conflict on link: detected on the first host probe (~50-300ms);
  service publication is skipped.
- Host unique, service conflict on link: host probe (750-1000ms)
  followed by the first service probe (0-250ms + RTT), taking
  ~750-1300ms total, which can exceed the default 1250ms timeout.
- Host unique, service conflict locally (`AlreadyPublishedLocally`):
  host probe (750-1000ms) plus 3 retries at 250ms (750ms), taking
  1500-1750ms total.
- No conflict (normal registration): host probe (750-1000ms) followed by
  service probe (750-1000ms; multiple services on the same host probe in
  parallel), taking 1500-2000ms total.

Setting the timeout to 2500ms provides sufficient headroom for all of
these scenarios without premature SRP server timeouts.

Original-Original-Bug: b/456808028
Test: fx build //src/connectivity/lowpan/drivers/lowpan-ot-driver:bin
Original-Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/openthread/+/1890553
Original-Original-Revision: c7d4295df1a3208c0dfb5f33ebfa508f8a9bb2ed

Original-Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1894274
Original-Original-Revision: fd0bfe915ec83ff872cfafd0a6527c7249c3ba31
GitOrigin-RevId: 60714a1b2f7df40858656a2a4ab6d4c06e57654b
Change-Id: Iac9a56caed3dec067cc6a01e7f40d5aac30378d7
Reviewed-on: https://fuchsia-review.googlesource.com/c/integration/+/1894423
Cr-Commit-Position: refs/heads/main@{#206601}

stem

diff --git a/stem b/stem
index 15cc68a..02bf8ce 100644
--- a/stem
+++ b/stem
@@ -8,6 +8,6 @@
             manifest="manifests/platform"
             root=""
             remote="https://fuchsia.googlesource.com/fuchsia"
-            revision="088a6edc59c19bbbf07595a403c0fac4bc233c6a"/>
+            revision="fd0bfe915ec83ff872cfafd0a6527c7249c3ba31"/>
   </imports>
 </manifest>