test(gemma): default integration test heap to 12g; merge duplicate Test blocks

The real-model FunctionGemma-270M integration tests (-PincludeIntegration)
OOM'd with `Java heap space` at the previous 8g default once the model file
is present: GemmaQ5KPackedParityTest holds the FP32 baseline plus both packed
decode networks at once, and the bake-to-irpa test holds weights + serialized
bytes simultaneously.

- Bump the `gemmaTestMaxHeap` default 8g -> 12g.
- Merge the two overlapping `tasks.withType<Test>().configureEach { }` blocks
  into one — the second silently overrode the first's maxHeapSize (so jvmArgs
  ran with 6g declared but 8g effective). Now jvmArgs, heap, and the seqLen
  system property live in a single block.

CI is unaffected: without the model file the integration tests self-skip and
never allocate the headroom. Verified: `:llm-inference:gemma:jvmTest
-PincludeIntegration` green with no -P override (87 tests, 6 skipped, 0
failures); GemmaQ5KPackedParityTest runs.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: michalharakal

llm-inference/gemma/build.gradle.kts

@@ -88,9 +88,16 @@ kotlin {
     }
 }
 
+// Real-model (FunctionGemma-270M) integration tests (run with -PincludeIntegration)
+// dequantize ~270M params to FP32, and GemmaQ5KPackedParityTest holds the FP32
+// baseline plus both packed decode networks at once; the bake-to-irpa test holds
+// weights + serialized bytes simultaneously. 8g OOMs once the real model is
+// present, so default to 12g — override via -PgemmaTestMaxHeap (CI without the
+// model file self-skips these and never needs the headroom).
 tasks.withType<Test>().configureEach {
     jvmArgs("--enable-preview", "--add-modules", "jdk.incubator.vector")
-    maxHeapSize = (findProperty("gemmaTestMaxHeap") as? String) ?: "6g"
+    maxHeapSize = (findProperty("gemmaTestMaxHeap") as? String) ?: "12g"
+    (findProperty("seqLen") as? String)?.let { systemProperty("seqLen", it) }
 }
 
 // Kotlin/JS + Kotlin/WASM browser test runners have two separate problems on
@@ -109,11 +116,3 @@ tasks.matching { it.name == "jsBrowserTest" || it.name == "wasmJsBrowserTest" }.
         ?.failOnNoDiscoveredTests = false
     enabled = includeBrowserTests
 }
-
-// Real-model (FunctionGemma-270M) tests dequantize ~270M params to FP32 and the
-// bake-to-irpa test holds weights + serialized bytes simultaneously; allow an
-// override via -PgemmaTestMaxHeap (default 8g).
-tasks.withType<Test>().configureEach {
-    maxHeapSize = (findProperty("gemmaTestMaxHeap") as? String) ?: "8g"
-    (findProperty("seqLen") as? String)?.let { systemProperty("seqLen", it) }
-}