Increased number of classes initialized during initialization of SignatureFileVerifier

While JDK-8155973 didn't cause any visible regression in 8u111-b09, we see a regression on jetty startup.

Startup profiling shows that the bulk of the difference between 9+141 and 9+142 comes due to eager loading of DisabledAlgorithmConstraints, which in turn initializes a few regex Patterns.

The reason using regex causes a startup regression in 9 but not in 8 is due to a set of changes going into 9+119 which added a lot of lambdas to j.u.regex, thus this issue might be considered a partial duplicate of JDK-8160302...

However, if we can avoid regular expressions in DisabledAlgorithmConstraints$Constraints - or only initialize them lazily, e.g. when detecting a key starting with denyAfter or keySize, respectively, we'd improve startup independently of whether or not JDK-8160302 gets a satisfactory resolution.