Rollup merge of #122437 - Nadrieril:no-after-max, r=compiler-errors

pattern analysis: remove `MaybeInfiniteInt::JustAfterMax`

It was inherited from before half-open ranges, but it doesn't pull its weight anymore. We lose a tiny bit of diagnostic precision as can be seen in the test. I'm generally in favor of half-open ranges over explicit `x..=MAX` ranges anyway.

compiler/rustc_pattern_analysis/src/rustc.rs

@@ -706,7 +706,7 @@ impl<'p, 'tcx: 'p> RustcPatCtxt<'p, 'tcx> {
                     None => PatRangeBoundary::PosInfinity,
                 }
             }
-            JustAfterMax | PosInfinity => PatRangeBoundary::PosInfinity,
+            PosInfinity => PatRangeBoundary::PosInfinity,
         }
     }