UnrecognizedClientException error when changing Access & secret key

[iwysiu]

This is the same issue as grafana/athena-datasource#246 , just in Redshift. Similarly, it can be reproduced by:
-create an IAM user with an access and secret key
-use those keys to create a Redshift datasource
-run an explore query with a schema selected
-create a new IAM user with the same permissions
-delete the old IAM user
-save the datasource with the keys from the new IAM user
-run an explore query with a schema selected (this should error)

It can be fixed the same way as grafana/athena-datasource#262 , by adding the updated time to the sqlds.Options passed to awsDS.GetDB, awsDS.GetAsyncDB, and awsDS.GetAPI