Remove cert auth (#5655)

This pull request removes `PATCH
Add-EKS-cluster-certificate_authorities-plural.patch` which was used to
address #1892 and ensure
backwards compatibility with pulumi-aws v4.

**This is a breaking change from v6.** Users will have to rename
`certificateAuthority` --> `certificateAuthorities`, but state migration
will be handled via the provider.

- Removes `PATCH Add-EKS-cluster-certificate_authorities-plural.patch`
and re-numbers patches
- Adds state migration for `certificateAuthority` ->
`certificateAuthorities`
- Migration is verified via existing EKSClusterUpgrade test.
- Updates upgrade guide.

Fixes #2733.

Author: guineveresaenger

docs/version-7-upgrade.md

@@ -58,6 +58,7 @@ Upgrade topics:
 * [Resource `aws.ecs.TaskDefinition`](#resource-awsecstaskdefinition)
 * [Resource `aws.ec2.Eip`](#resource-awsec2eip)
 * [Resource `aws.eks.Addon`](#resource-awseksaddon)
+* [Resource `aws.eks.Cluster`](#resource-awsekscluster)
 * [Resource `aws.elasticache.ReplicationGroup`](#resource-awselasticachereplicationgroup)
 * [Resource `aws.elasticache.User`](#resource-awselasticacheuser)
 * [Resource `aws.elasticache.UserGroup`](#resource-awselasticacheusergroup)
@@ -709,6 +710,10 @@ Remove `vpc`—it is no longer supported. Use `domain` instead.
 
 Remove `resolveConflicts`—it is no longer supported. Use `resolveConflictsOnCreate` and `resolveConflictsOnUpdate` instead.
 
+## Resource `aws.eks.Cluster`
+
+`certificateAuthority` is no longer supported. Use `certificateAuthorities` instead.
+
 ## Resource `aws.elasticache.ReplicationGroup`
 
 * `authTokenUpdateStrategy` no longer has a default value. If `authToken` is set, it must also be explicitly configured.