Default IdC login region to user-defined region, otherwise us-east-1 (#4445)

Slightly improve login UX by having a region pre-selected on first login

Author: rli

plugins/core/jetbrains-community/src/software/aws/toolkits/jetbrains/core/credentials/DefaultToolkitAuthManager.kt

@@ -18,6 +18,7 @@ import software.aws.toolkits.core.utils.warn
 import software.aws.toolkits.jetbrains.core.credentials.profiles.ProfileSsoSessionIdentifier
 import software.aws.toolkits.jetbrains.core.credentials.sono.SONO_URL
 import software.aws.toolkits.jetbrains.core.credentials.sso.bearer.BearerTokenProviderListener
+import software.aws.toolkits.jetbrains.core.region.AwsRegionProvider
 import java.util.Collections
 
 typealias ToolkitAuthManager = migration.software.aws.toolkits.jetbrains.core.credentials.ToolkitAuthManager
@@ -303,5 +304,5 @@ data class ToolkitAuthManagerState(
 data class LastLoginIdcInfo(
     var profileName: String = "",
     var startUrl: String = "",
-    var region: String = ""
+    var region: String = AwsRegionProvider.getInstance().defaultRegion().id
 )