Fix search attribute creation race

[awln-temporal]

What changed?

Add check for duplicate aliases when registering search attributes in UpdateNamespace handler.

Why?

Registering search attributes through Operator handler checks for already registered aliases and fields, but this initial read has no checks for the version of the Namespace Config. UpdateNamespace handler does another read of the namespace config before attempting to write with the Config version as optimistic concurrency control, but this last validation only checks for competing field names. So, if a user registers the same search attribute alias at the same time, they can both be treated as valid updates, leading to undefined behavior when querying from visibility.

How did you test it?

• built
• run locally and tested manually
• covered by existing tests
• added new unit test(s)
• added new functional test(s)

[rodrigozhou]

nit

Suggested change

	} else if _, ok := current[key]; !ok {
	if _, aliasExists := currentAliasToField[value]; aliasExists {
	d.logger.Warn(
	fmt.Sprintf(errSearchAttributeAlreadyExistsMessage, value),
	tag.String("visibility-search-attribute", value),
	)
	continue
	}
	result[key] = value
	} else {
	} else if _, aliasExists := currentAliasToField[value]; aliasExists {
	d.logger.Warn(
	fmt.Sprintf(errSearchAttributeAlreadyExistsMessage, value),
	tag.String("visibility-search-attribute", value),
	)
	continue
	} else if _, ok := current[key]; !ok {
	result[key] = value
	} else {