perf: reduce Java E2E looping time to 5s and cache runtime JAR build

Make TOTAL_LOOPING_TIME configurable via CODEFLASH_LOOPING_TIME env var
(defaults to 10s). Set to 5s in Java E2E CI jobs to cut verification
time per candidate. Also cache the codeflash-runtime JAR keyed on
source hash to skip mvn install when unchanged.

.github/workflows/ci.yaml

@@ -436,6 +436,7 @@ jobs:
       RETRY_DELAY: 5
       EXPECTED_IMPROVEMENT_PCT: ${{ matrix.expected_improvement }}
       CODEFLASH_END_TO_END: 1
+      CODEFLASH_LOOPING_TIME: 5
     steps:
       - uses: actions/checkout@v6
         with:
@@ -469,7 +470,15 @@ jobs:
       - name: Install dependencies
         run: uv sync
 
+      - name: Cache codeflash-runtime JAR
+        id: runtime-jar-cache
+        uses: actions/cache@v4
+        with:
+          path: ~/.m2/repository/io/codeflash
+          key: codeflash-runtime-${{ hashFiles('codeflash-java-runtime/pom.xml', 'codeflash-java-runtime/src/**') }}
+
       - name: Build and install codeflash-runtime JAR
+        if: steps.runtime-jar-cache.outputs.cache-hit != 'true'
         run: |
           cd codeflash-java-runtime
           mvn install -q -DskipTests

codeflash/code_utils/config_consts.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import os
 from enum import Enum
 from typing import Any, Union
 
@@ -17,7 +18,7 @@ MIN_CONCURRENCY_IMPROVEMENT_THRESHOLD = 0.20  # 20% concurrency ratio improvemen
 CONCURRENCY_FACTOR = 10  # Number of concurrent executions for concurrency benchmark
 MAX_TEST_FUNCTION_RUNS = 50
 MAX_CUMULATIVE_TEST_RUNTIME_NANOSECONDS = 100e6  # 100ms
-TOTAL_LOOPING_TIME = 10.0  # 10 second candidate benchmarking budget
+TOTAL_LOOPING_TIME = float(os.getenv("CODEFLASH_LOOPING_TIME", "10.0"))  # candidate benchmarking budget (seconds)
 COVERAGE_THRESHOLD = 60.0
 MIN_TESTCASE_PASSED_THRESHOLD = 6
 REPEAT_OPTIMIZATION_PROBABILITY = 0.1