resource/aws_elasticache_parameter_group: Remove deprecated (helper/s…

…chema.ResourceData).Partial() and (helper/schema.ResourceData).SetPartial() (hashicorp#12471)

Reference: hashicorp#12083
Reference: hashicorp#12087

Previously:

```
aws/resource_aws_elasticache_parameter_group.go:136:2: R007: deprecated (schema.ResourceData).Partial
aws/resource_aws_elasticache_parameter_group.go:310:3: R008: deprecated (schema.ResourceData).SetPartial
aws/resource_aws_elasticache_parameter_group.go:313:2: R007: deprecated (schema.ResourceData).Partial
aws/resource_aws_elasticache_parameter_group.go:84:2: R007: deprecated (schema.ResourceData).Partial
aws/resource_aws_elasticache_parameter_group.go:85:2: R008: deprecated (schema.ResourceData).SetPartial
aws/resource_aws_elasticache_parameter_group.go:86:2: R008: deprecated (schema.ResourceData).SetPartial
aws/resource_aws_elasticache_parameter_group.go:87:2: R008: deprecated (schema.ResourceData).SetPartial
aws/resource_aws_elasticache_parameter_group.go:88:2: R007: deprecated (schema.ResourceData).Partial
```

Output from acceptance testing:

```
--- PASS: TestAccAWSElasticacheParameterGroup_Description (23.39s)
--- PASS: TestAccAWSElasticacheParameterGroup_basic (25.25s)
--- PASS: TestAccAWSElasticacheParameterGroup_UppercaseName (25.32s)
--- PASS: TestAccAWSElasticacheParameterGroup_removeReservedMemoryParameter (42.06s)
--- PASS: TestAccAWSElasticacheParameterGroup_removeAllParameters (44.50s)
--- PASS: TestAccAWSElasticacheParameterGroup_addParameter (44.70s)
--- PASS: TestAccAWSElasticacheParameterGroup_updateReservedMemoryParameter (90.73s)
--- PASS: TestAccAWSElasticacheParameterGroup_switchReservedMemoryParameter (91.11s)
```

aws/resource_aws_elasticache_parameter_group.go

@@ -81,12 +81,6 @@ func resourceAwsElasticacheParameterGroupCreate(d *schema.ResourceData, meta int
 		return fmt.Errorf("Error creating Cache Parameter Group: %s", err)
 	}
 
-	d.Partial(true)
-	d.SetPartial("name")
-	d.SetPartial("family")
-	d.SetPartial("description")
-	d.Partial(false)
-
 	d.SetId(*resp.CacheParameterGroup.CacheParameterGroupName)
 	log.Printf("[INFO] Cache Parameter Group ID: %s", d.Id())
 
@@ -133,8 +127,6 @@ func resourceAwsElasticacheParameterGroupRead(d *schema.ResourceData, meta inter
 func resourceAwsElasticacheParameterGroupUpdate(d *schema.ResourceData, meta interface{}) error {
 	conn := meta.(*AWSClient).elasticacheconn
 
-	d.Partial(true)
-
 	if d.HasChange("parameter") {
 		o, n := d.GetChange("parameter")
 		if o == nil {
@@ -306,12 +298,8 @@ func resourceAwsElasticacheParameterGroupUpdate(d *schema.ResourceData, meta int
 				return fmt.Errorf("Error modifying Cache Parameter Group: %s", err)
 			}
 		}
-
-		d.SetPartial("parameter")
 	}
 
-	d.Partial(false)
-
 	return resourceAwsElasticacheParameterGroupRead(d, meta)
 }