fix(python): regex injection not working for concatenated strings (#8197)

Co-authored-by: Riley Bruins <ribru17@hotmail.com>

tests/query/highlights/starlark/test.bzl

@@ -0,0 +1,11 @@
+# split
+# ^ @comment
+assert_eq('foo bar'.split(' '), ['foo', 'bar'])
+# ^ @keyword
+#        ^ @punctuation.bracket
+#          ^ @string
+#                  ^ @punctuation.delimiter
+assert_eq('foo bar foo'.rsplit(' ', 1), ['foo bar', 'foo'])
+#                                   ^ @number
+assert_eq("foo %s bar %d" % ("arg1", 2), "foo arg1 bar 2")
+#              ^ @character