Refine AntPathMatcher.combine rules to allow direct concatenation of
patterns when pattern1 does not contain '*.'. Prior to this commit
direct concatenation was allowed when pattern1 did not contain '.',
this prevented calls of the form:
pathMatcher.combine("/1.0", "/foo/test")
from working as expected.
This commit also applies some general cleanup to the `combine` method.
Issue: SPR-10554