Remove NewRegexpMatcher and panic on error instead

Signed-off-by: Kiril Vladimirov <kiril@vladimiroff.org>

pkg/labels/matcher.go

@@ -152,11 +152,3 @@ func (ms Matchers) String() string {
 
 	return buf.String()
 }
-
-// NewRegexpMatcher returns a matcher with already compiled regexp.Regexp.
-//
-// TODO(vladimiroff): Get rid of this function once migration from
-// types.Matcher is complete.
-func NewRegexpMatcher(n string, re *regexp.Regexp) *Matcher {
-	return &Matcher{Type: MatchRegexp, Name: n, Value: re.String(), re: re}
-}