MB-53920: Rename NeedsRecovery into HighAndNeedsRecovery

In preparation for introducing the CheckpointMemoryState::High entry,
which will indicate a state where the overall checkpoint allocation in
the system is high but we don't want to trigger mem-recovery from CM.

Change-Id: I81cc7ac6bdc988114806a10a460b5d7cbdbed186
Reviewed-on: https://review.couchbase.org/c/kv_engine/+/181048
Reviewed-by: Dave Rigby <daver@couchbase.com>
Tested-by: Build Bot <build@couchbase.com>

engines/ep/src/kv_bucket.cc

@@ -2989,7 +2989,7 @@ KVBucket::CheckpointMemoryState KVBucket::getCheckpointMemoryState() const {
     if (usage < recoveryThreshold) {
         return CheckpointMemoryState::Available;
     } else if (usage < checkpointQuota) {
-        return CheckpointMemoryState::NeedsRecovery;
+        return CheckpointMemoryState::HighAndNeedsRecovery;
     } else {
         return CheckpointMemoryState::Full;
     }
@@ -3002,7 +3002,7 @@ KVBucket::CheckpointMemoryState KVBucket::verifyCheckpointMemoryState() {
     switch (state) {
     case CheckpointMemoryState::Available:
         break;
-    case CheckpointMemoryState::NeedsRecovery:
+    case CheckpointMemoryState::HighAndNeedsRecovery:
     case CheckpointMemoryState::Full:
         wakeUpCheckpointMemRecoveryTask();
         break;

engines/ep/src/kv_bucket.h

@@ -866,7 +866,7 @@ class KVBucket : public KVBucketIface {
 
     enum class CheckpointMemoryState : uint8_t {
         Available,
-        NeedsRecovery,
+        HighAndNeedsRecovery,
         Full
     };