Increase BootstrappedOnlyCompilationTests timeout

Some of the tests in this file are a bit heavy and tend to timeout when
the CI is overloaded.

Tests that take may take longer include tests with the tasty inspector and
the staging tests.

[Cherry-picked fcc6fca]

Author: nicolasstucki

compiler/test/dotty/tools/dotc/BootstrappedOnlyCompilationTests.scala

@@ -206,7 +206,7 @@ class BootstrappedOnlyCompilationTests {
 object BootstrappedOnlyCompilationTests extends ParallelTesting {
   // Test suite configuration --------------------------------------------------
 
-  def maxDuration = 60.seconds
+  def maxDuration = 100.seconds
   def numberOfSlaves = Runtime.getRuntime().availableProcessors()
   def safeMode = Properties.testsSafeMode
   def isInteractive = SummaryReport.isInteractive