…iations/propagations as missing
Previously:
```
--- FAIL: TestAccAWSEc2TransitGatewayVpcAttachment_TransitGatewayDefaultRouteTableAssociationAndPropagationDisabled (87.32s)
testing.go:538: Step 0 error: Error applying: 1 error occurred:
* aws_ec2_transit_gateway_vpc_attachment.test: 1 error occurred:
* aws_ec2_transit_gateway_vpc_attachment.test: error updating EC2 Transit Gateway Attachment (tgw-attach-0e5e1795143bd2b2e) Route Table () association: error determining EC2 Transit Gateway Attachment Route Table () association (tgw-attach-0e5e1795143bd2b2e): MissingParameter: Missing required parameter in request: TransitGatewayRouteTableId.
```
Output from acceptance testing:
```
--- PASS: TestAccAWSEc2TransitGateway_AmazonSideASN (282.51s)
--- PASS: TestAccAWSEc2TransitGateway_AutoAcceptSharedAttachments (282.79s)
--- PASS: TestAccAWSEc2TransitGateway_basic (119.74s)
--- PASS: TestAccAWSEc2TransitGateway_DefaultRouteTableAssociation (304.57s)
--- PASS: TestAccAWSEc2TransitGateway_DefaultRouteTableAssociationAndPropagationDisabled (97.26s)
--- PASS: TestAccAWSEc2TransitGateway_DefaultRouteTablePropagation (292.85s)
--- PASS: TestAccAWSEc2TransitGateway_Description (303.75s)
--- PASS: TestAccAWSEc2TransitGateway_disappears (133.04s)
--- PASS: TestAccAWSEc2TransitGateway_DnsSupport (294.91s)
--- PASS: TestAccAWSEc2TransitGateway_Tags (142.00s)
--- PASS: TestAccAWSEc2TransitGateway_VpnEcmpSupport (262.29s)
--- PASS: TestAccAWSEc2TransitGatewayDataSource_Filter (149.81s)
--- PASS: TestAccAWSEc2TransitGatewayDataSource_ID (150.09s)
--- PASS: TestAccAWSEc2TransitGatewayRoute_basic (199.22s)
--- PASS: TestAccAWSEc2TransitGatewayRoute_disappears (274.00s)
--- PASS: TestAccAWSEc2TransitGatewayRouteTable_basic (180.87s)
--- PASS: TestAccAWSEc2TransitGatewayRouteTable_disappears (222.99s)
--- PASS: TestAccAWSEc2TransitGatewayRouteTable_disappears_TransitGateway (151.50s)
--- PASS: TestAccAWSEc2TransitGatewayRouteTable_Tags (207.50s)
--- PASS: TestAccAWSEc2TransitGatewayRouteTableAssociation_basic (274.40s)
--- PASS: TestAccAWSEc2TransitGatewayRouteTableDataSource_Filter (194.26s)
--- PASS: TestAccAWSEc2TransitGatewayRouteTableDataSource_ID (182.70s)
--- PASS: TestAccAWSEc2TransitGatewayRouteTablePropagation_basic (237.60s)
--- PASS: TestAccAWSEc2TransitGatewayVpcAttachment_basic (205.70s)
--- PASS: TestAccAWSEc2TransitGatewayVpcAttachment_disappears (210.35s)
--- PASS: TestAccAWSEc2TransitGatewayVpcAttachment_DnsSupport (241.30s)
--- PASS: TestAccAWSEc2TransitGatewayVpcAttachment_Ipv6Support (267.59s)
--- PASS: TestAccAWSEc2TransitGatewayVpcAttachment_SubnetIds (370.24s)
--- PASS: TestAccAWSEc2TransitGatewayVpcAttachment_Tags (294.68s)
--- PASS: TestAccAWSEc2TransitGatewayVpcAttachment_TransitGatewayDefaultRouteTableAssociation (330.97s)
--- PASS: TestAccAWSEc2TransitGatewayVpcAttachment_TransitGatewayDefaultRouteTableAssociationAndPropagationDisabled (212.14s)
--- PASS: TestAccAWSEc2TransitGatewayVpcAttachment_TransitGatewayDefaultRouteTablePropagation (275.11s)
--- PASS: TestAccAWSEc2TransitGatewayVpcAttachmentDataSource_Filter (206.94s)
--- PASS: TestAccAWSEc2TransitGatewayVpcAttachmentDataSource_ID (207.48s)
```