tests: Fix allocative test in starlark CI

Summary:
This test is failing in the OSS jobs - I expect that's probably the result of some version mismatch or other difference in the environment/optimizations causing slight changes in how much unused capacity `String`s allocate by default. Just adjust the test to not depend on that value

Also adjust the filegroup so that updating the test fixtures works from buck

Reviewed By: rajneesh

Differential Revision: D77272283

fbshipit-source-id: b07987997bb4f9ce63bb7300628e7119f10cb53d

Author: JakobDegen

allocative/allocative/src/impls/hashbrown.rs

@@ -61,7 +61,9 @@ mod tests {
     fn test_hash_table() {
         let mut table = HashTable::with_capacity(100);
         for i in 0..100 {
-            table.insert_unique(hash(&i.to_string()), i.to_string(), hash);
+            let mut s = i.to_string();
+            s.shrink_to_fit(); // Make the string deterministically sized
+            table.insert_unique(hash(&s), s, hash);
         }
 
         golden_test!(&table);

allocative/allocative/src/impls/hashbrown_test_hash_table.src

@@ -9,4 +9,3 @@ hashbrown::table::HashTable<alloc::string::String>;data;capacity 800
 hashbrown::table::HashTable<alloc::string::String>;data;capacity;alloc::string::String 1600
 hashbrown::table::HashTable<alloc::string::String>;data;capacity;alloc::string::String;ptr 800
 hashbrown::table::HashTable<alloc::string::String>;data;capacity;alloc::string::String;ptr;capacity;u8 190
-hashbrown::table::HashTable<alloc::string::String>;data;capacity;alloc::string::String;ptr;capacity;unused_capacity 610