Use StringBuilder intead of StringBuffer in Regex

[xuwei-k]

• https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/regex/Matcher.html#appendTail(java.lang.StringBuilder)
• Dubious string buffer [ci: last-only] scala#11061

[xuwei-k]

• Support java.util.regex.Matcher#appendTail with StringBuilder param scala-js/scala-js#5261

scala-js job failed 😢

Referring to non-existent method java.util.regex.Matcher.appendTail(java.lang.StringBuilder)java.lang.StringBuilder
  dispatched from java.util.regex.Matcher.appendTail(java.lang.StringBuilder)java.lang.StringBuilder
  called from scala.util.matching.Regex$Replacement.replaced()java.lang.String
  called from scala.util.matching.Regex.replaceSomeIn(java.lang.CharSequence,scala.Function1)java.lang.String
  called from Test$.replacementMatching()void
  called from Test$.main([java.lang.String)void
  called from static Test.main([java.lang.String)void
  called from core module module initializers