MB-53954 Use specified memory quota for calculation

1. If memory_quota is specified, use that for calculation
2. If "batch_size" option is specified in the WITH clause,
   do not recalculate and reset batch_size.

Change-Id: Ib710e8342646bd9e5664fb32bee78a09e1c05d8d
Reviewed-on: https://review.couchbase.org/c/query/+/180980
Reviewed-by: Sitaram Vemulapalli <sitaram.vemulapalli@couchbase.com>
Tested-by: Bingjie Miao <bingjie.miao@couchbase.com>

execution/context.go

@@ -663,6 +663,10 @@ func (this *Context) UseRequestQuota() bool {
 	return this.memorySession != nil
 }
 
+func (this *Context) MemoryQuota() uint64 {
+	return this.memoryQuota
+}
+
 func (this *Context) ProducerThrottleQuota() uint64 {
 	return this.memoryQuota / 10
 }