Fix Failing TranslogTests.testRecoveryFromFailureOnTrimming (#82148) (#…

…82150)

In #77674 the assertion that is moved here was added.
The problem with it is that when running tests that do
random IO exceptions on the `channel.position()` call,
the assertion actual has a side effect.
If the exception it triggers as a side effect is not caught and
the translog failed as a result, tests around the safety of handling
IOExceptions in this code fail. Unfortunately, the assertion still
has a side effect after this change but its side effect is handled
like an expected IOException.

server/src/main/java/org/elasticsearch/index/translog/TranslogWriter.java

@@ -478,11 +478,11 @@ final boolean syncUpTo(long offset) throws IOException {
                         try {
                             // Write ops will release operations.
                             writeAndReleaseOps(toWrite);
+                            assert channel.position() == checkpointToSync.offset;
                         } catch (final Exception ex) {
                             closeWithTragicEvent(ex);
                             throw ex;
                         }
-                        assert channel.position() == checkpointToSync.offset;
                     }
                     // now do the actual fsync outside of the synchronized block such that
                     // we can continue writing to the buffer etc.