java-sdk: compile the entrypoint against the prebuilt SDK jars [1B]

Pass -Ddagger.sdk=prebuilt to the entrypoint compile so it activates the
dagger-prebuilt-sdk profile and compiles only the module's own sources against
the SDK jars installed by vendoredSdk, instead of recompiling the ~146 vendored
SDK source files on every generate. Revert just this commit to fall back to the
source-compiled entrypoint.

Signed-off-by: Yves Brissaud <yves@dagger.io>

Author: eunomie

mod.dang

@@ -134,7 +134,7 @@ type Mod {
       .withDirectory("/module", moduleDir)
       .withWorkdir("/module")
       .withEnvVariable("_DAGGER_JAVA_SDK_MODULE_NAME", name)
-      .withExec(["mvn", "compile", "-Ddagger.proc=full", "--no-transfer-progress"])
+      .withExec(["mvn", "compile", "-Ddagger.proc=full", "-Ddagger.sdk=prebuilt", "--no-transfer-progress"])
       .directory("/module/target/generated-sources/annotations")
   }