resource/aws_lambda_function: Properly handle vpc_config removal

[bflad]

Includes preventing panics as started by #5792

Fixes #5791
Fixes #3784
Fixes #2509

Changes proposed in this pull request:

• Adds acceptance test (TestAccAWSLambdaFunction_VPCRemoval) to cover vpc_config removal
• Prevents panic when removing vpc_config
• Properly handles vpc_config removal to prevent perpetual difference

Previously:

--- FAIL: TestAccAWSLambdaFunction_VPCRemoval (42.52s)
    testing.go:527: Step 1 error: Check failed: Check 2/2 error: aws_lambda_function.lambda_function_test: Attribute 'vpc_config.#' expected "0", got "1"

Output from acceptance testing: (others pending in TeamCity)

31 tests passed (all tests)
--- PASS: TestAccAWSLambdaFunction_nilDeadLetterConfig (17.96s)
--- PASS: TestAccAWSLambdaFunction_importS3 (21.54s)
--- PASS: TestAccAWSLambdaFunction_expectFilenameAndS3Attributes (27.06s)
--- PASS: TestAccAWSLambdaFunction_versioned (30.83s)
--- PASS: TestAccAWSLambdaFunction_basic (37.09s)
--- PASS: TestAccAWSLambdaFunction_importLocalFile (37.63s)
--- PASS: TestAccAWSLambdaFunction_runtimeValidation_noRuntime (0.48s)
--- PASS: TestAccAWSLambdaFunction_updateRuntime (39.90s)
--- PASS: TestAccAWSLambdaFunction_DeadLetterConfigUpdated (48.67s)
--- PASS: TestAccAWSLambdaFunction_VPCRemoval (50.55s)
--- PASS: TestAccAWSLambdaFunction_VPC (51.22s)
--- PASS: TestAccAWSLambdaFunction_localUpdate (30.33s)
--- PASS: TestAccAWSLambdaFunction_s3 (35.32s)
--- PASS: TestAccAWSLambdaFunction_localUpdate_nameOnly (32.29s)
--- PASS: TestAccAWSLambdaFunction_versionedUpdate (62.81s)
--- PASS: TestAccAWSLambdaFunction_s3Update_unversioned (29.28s)
--- PASS: TestAccAWSLambdaFunction_tracingConfig (66.61s)
--- PASS: TestAccAWSLambdaFunction_s3Update_basic (37.50s)
--- PASS: TestAccAWSLambdaFunction_DeadLetterConfig (69.89s)
--- PASS: TestAccAWSLambdaFunction_importLocalFile_VPC (76.53s)
--- PASS: TestAccAWSLambdaFunction_runtimeValidation_nodeJs43 (38.74s)
--- PASS: TestAccAWSLambdaFunction_concurrency (77.12s)
--- PASS: TestAccAWSLambdaFunction_runtimeValidation_python27 (40.97s)
--- PASS: TestAccAWSLambdaFunction_runtimeValidation_python36 (30.25s)
--- PASS: TestAccAWSLambdaFunction_VPCUpdate (81.65s)
--- PASS: TestAccAWSLambdaFunction_runtimeValidation_java8 (35.09s)
--- PASS: TestAccAWSLambdaFunction_concurrencyCycle (88.68s)
--- PASS: TestAccAWSLambdaFunction_envVariables (89.78s)
--- PASS: TestAccAWSLambdaFunction_tags (40.89s)
--- PASS: TestAccAWSLambdaFunction_encryptedEnvVariables (94.16s)
--- PASS: TestAccAWSLambdaFunction_VPC_withInvocation (119.74s)

[mbfrahry]

LGTM!

[bflad]

This has been released in version 1.35.0 of the AWS provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!