fix: displayName equality is high-confidence without metadata signals (CM-1137)

decideMemberSimilarityUsingAdditionalChecks returned LOW_CONFIDENCE_SCORE (0.2)
when called from the displayName equality path with no metadata signals, even though
the displayName match itself is already high-confidence. Initialise isHighConfidence=true
when no startingScore is provided so the function returns at least 0.9.

Signed-off-by: Yeganathan S <63534555+skwowet@users.noreply.github.com>

Author: skwowet

services/apps/merge_suggestions_worker/src/memberSimilarityCalculator.ts

@@ -464,8 +464,10 @@ class MemberSimilarityCalculator {
     similarMember: IMemberOpensearch,
     startingScore?: number,
   ): number {
-    let isHighConfidence = false
-    let confidenceScore = startingScore || this.HIGH_CONFIDENCE_SCORE
+    // displayName equality (startingScore omitted) is itself a high-confidence signal — don't
+    // gate on metadata. Edit-distance callers pass a score and must have at least one signal.
+    let isHighConfidence = startingScore === undefined
+    let confidenceScore = startingScore ?? this.HIGH_CONFIDENCE_SCORE
 
     const bumpFactor = (1 - confidenceScore) / 5