feat(tests): add min_amount parameter to pool_user functions

Added a `min_amount` parameter to `pool_user`, `pool_user_lg`, and
`pool_user_ug` functions in `test_committee.py`. This ensures better
control over minimum required amounts for testing scenarios.

Author: mkoura

cardano_node_tests/tests/tests_conway/test_committee.py

@@ -67,6 +67,8 @@ def pool_user(
         cluster_manager=cluster_manager,
         cluster_obj=cluster,
         caching_key=key,
+        amount=350_000_000,
+        min_amount=250_000_000,
     )
 
 
@@ -84,7 +86,8 @@ def pool_user_lg(
         cluster_manager=cluster_manager,
         cluster_obj=cluster,
         caching_key=key,
-        amount=500_000_000,
+        amount=400_000_000,
+        min_amount=350_000_000,
     )
 
 
@@ -103,6 +106,7 @@ def pool_user_ug(
         cluster_obj=cluster,
         caching_key=key,
         amount=300_000_000,
+        min_amount=250_000_000,
     )