Remove HashSet initialization with capacity

Author: ArunPiduguDD

changelog.d/tag_cardinality_limit_improve_memory_usage.enhancement.md

@@ -0,0 +1,3 @@
+Reduce the memory usage of the `tag_cardinality_limit` transform when running in `exact` mode by allocating less unused memory on initialization.
+
+authors: ArunPiduguDD

src/transforms/tag_cardinality_limit/tag_value_set.rs

@@ -60,8 +60,9 @@ impl fmt::Debug for TagValueSetStorage {
 
 impl AcceptedTagValueSet {
     pub fn new(value_limit: usize, mode: &Mode) -> Self {
+        let _ = value_limit; // capacity is grown lazily; `value_limit` only caps `len()` at insert time
         let storage = match &mode {
-            Mode::Exact => TagValueSetStorage::Set(HashSet::with_capacity(value_limit)),
+            Mode::Exact => TagValueSetStorage::Set(HashSet::new()),
             Mode::Probabilistic(config) => {
                 TagValueSetStorage::Bloom(BloomFilterStorage::new(config.cache_size_per_key))
             }