Fix compilation with Regex being disabled (open-telemetry#3276)

* Fix compilation with Regex disabled:
* It was missing an include for std::any_of
* Avoid declaring unused constants (at least my LLVM errors out)

* Only include algorithm if needed.

* Fix where we reference the WORKING_REGEX.

Author: kylepl

sdk/src/metrics/instrument_metadata_validator.cc

@@ -9,18 +9,22 @@
 
 #if OPENTELEMETRY_HAVE_WORKING_REGEX
 #  include <regex>
+#else
+#  include <algorithm>
 #endif
 
 OPENTELEMETRY_BEGIN_NAMESPACE
 namespace sdk
 {
 namespace metrics
 {
+#if OPENTELEMETRY_HAVE_WORKING_REGEX
 // instrument-name = ALPHA 0*254 ("_" / "." / "-" / "/" / ALPHA / DIGIT)
 const std::string kInstrumentNamePattern = "[a-zA-Z][-_./a-zA-Z0-9]{0,254}";
 //
 const std::string kInstrumentUnitPattern = "[\x01-\x7F]{0,63}";
 // instrument-unit = It can have a maximum length of 63 ASCII chars
+#endif
 
 InstrumentMetaDataValidator::InstrumentMetaDataValidator()
 #if OPENTELEMETRY_HAVE_WORKING_REGEX