Fix: Prevent GADT reasoning in pattern alternatives

[Linyxus]

fixes #22805.

[dwijnand]

I guess this is the minimal sound but not complete fix, which is the right initial choice, so LGTM to merge.

[dwijnand]

The alternative would be to leverage InPatternAlternative in the various parts where GADT reasoning is employed.

[Linyxus]

Seems that the community build fails on the merging commit; I checked the trace but it seems quite irrelevant. Looks like a random failure?

[dwijnand]

Yes:

Error: All tests passed after retry, indicating that some tests are flaky.
Error: This build is configured to reject flaky tests.

[dwijnand]

failing seed for hash.same as scala hashing is 02q7JmTZisk304fqzp3dLoasNHF2CNaWFypvZ7ENAhE=
failing seed for hash.same as scala hashing is Csk-rxF6Fu7wpOPKgrGSPkxdWfc2x5NtYbLDdFncwAD=
[error] ==> X cats.tests.ArraySeqSuite.ArraySeq[Int]: hash.same as scala hashing  0.049s munit.FailException: /__w/scala3/scala3/community-build/community-projects/cats/tests/shared/src/test/scala-2.13+/cats/tests/ArraySeqSuite.scala:81
[error] 80:    implicit val hash: Hash[ListWrapper[Int]] = ListWrapper.hash[Int]
[error] 81:    checkAll("ArraySeq[Int]", HashTests[ArraySeq[ListWrapper[Int]]].hash)
[error] 82:    checkAll("Hash[ArraySeq]", SerializableTests.serializable(Hash[ArraySeq[ListWrapper[Int]]]))
[error] 
[error] Failing seed: _7kS1maL5k9NcZRO4TRUfIVMHJormxFh7Pv-waVX43K=
[error] You can reproduce this failure by adding the following override to your suite:
[error] 
[error]   override val scalaCheckInitialSeed = "_7kS1maL5k9NcZRO4TRUfIVMHJormxFh7Pv-waVX43K="
[error] 
[error] Falsified after 44 passed tests.
[error] > Labels of failing property: 
[error] Expected: true
[error] Received: false
[error] > ARG_0: ArraySeq(ListWrapper(List(348318819)), ListWrapper(List()), ListWrapper(List(-1210464944, -2147483648, 2147483647, -1, 963531488, 1979816629)), ListWrapper(List(1082445307, -1008730567, -311475957, -264455900, 0, -1806307621, -415030663, 1412610993, -2147483648)), ListWrapper(List(-1, -1, -109795631, 697642861)), ListWrapper(List(1, 1, 1)))
[error] > ARG_1: ArraySeq(ListWrapper(List(1585039739)))
[error]     at munit.Assertions.fail(Assertions.scala:283)
[error]     at munit.Assertions.fail$(Assertions.scala:15)
[error]     at munit.FunSuite.fail(FunSuite.scala:11)
[error]     at munit.ScalaCheckSuite.propToTry$$anonfun$1(ScalaCheckSuite.scala:104)
[error]     at scala.util.Try$.apply(Try.scala:217)
[error]     at munit.ScalaCheckSuite.propToTry(ScalaCheckSuite.scala:104)
[error]     at munit.ScalaCheckSuite.$init$$$anonfun$1$$anonfun$1$$anonfun$1(ScalaCheckSuite.scala:46)
[error]     at scala.concurrent.impl.Promise$Transformation.run(Promise.scala:475)
[error]     at munit.Suite$$anon$1.execute(Suite.scala:26)
[error]     at scala.concurrent.impl.Promise$Transformation.submitWithValue(Promise.scala:429)
[error]     at scala.concurrent.impl.Promise$DefaultPromise.submitWithValue(Promise.scala:338)
[error]     at scala.concurrent.impl.Promise$DefaultPromise.dispatchOrAddCallbacks(Promise.scala:312)
[error]     at scala.concurrent.impl.Promise$DefaultPromise.transform(Promise.scala:128)
[error]     at munit.internal.FutureCompat$ExtensionFuture.transformCompat(FutureCompat.scala:16)
[error]     at munit.ScalaCheckSuite.$init$$$anonfun$1$$anonfun$1(ScalaCheckSuite.scala:48)
[error]     at munit.GenericTest.withBodyMap$$anonfun$1(GenericTest.scala:33)
[error]     at munit.MUnitRunner.$anonfun$10(MUnitRunner.scala:296)
[error] Failed: Total 12846, Failed 1, Errors 0, Passed 12845
[error] Failed tests:
[error] 	cats.tests.ArraySeqSuite