fix(gradle): Use gradle wrapper inside docker (#5598)

lib/manager/gradle/__snapshots__/index.spec.ts.snap

@@ -508,7 +508,7 @@ Array [
 exports[`manager/gradle extractPackageFile should use docker even if gradlew is available 1`] = `
 Array [
   Object {
-    "cmd": "docker run --rm -v \\"localDir\\":\\"localDir\\" -w \\"localDir\\" renovate/gradle bash -l -c \\"gradle --init-script renovate-plugin.gradle renovate\\"",
+    "cmd": "docker run --rm -v \\"localDir\\":\\"localDir\\" -w \\"localDir\\" renovate/gradle bash -l -c \\"./gradlew --init-script renovate-plugin.gradle renovate\\"",
     "options": Object {
       "cwd": "localDir",
       "encoding": "utf-8",
@@ -536,7 +536,7 @@ Array [
     },
   },
   Object {
-    "cmd": "docker run --rm -v \\"localDir\\":\\"localDir\\" -w \\"localDir\\" renovate/gradle bash -l -c \\"gradle --init-script renovate-plugin.gradle renovate\\"",
+    "cmd": "docker run --rm -v \\"localDir\\":\\"localDir\\" -w \\"localDir\\" renovate/gradle bash -l -c \\"./gradlew --init-script renovate-plugin.gradle renovate\\"",
     "options": Object {
       "cwd": "localDir",
       "encoding": "utf-8",

lib/manager/gradle/index.ts

@@ -24,7 +24,6 @@ import {
 import { platform } from '../../platform';
 import { LANGUAGE_JAVA } from '../../constants/languages';
 import { DATASOURCE_MAVEN } from '../../constants/data-binary-source';
-import { BinarySource } from '../../util/exec/common';
 import { DatasourceError } from '../../datasource';
 
 export const GRADLE_DEPENDENCY_REPORT_OPTIONS =
@@ -46,8 +45,6 @@ async function getGradleCommandLine(
 ): Promise<string> {
   const args = GRADLE_DEPENDENCY_REPORT_OPTIONS;
 
-  if (config.binarySource === BinarySource.Docker) return `gradle ${args}`;
-
   const gradlewPath = upath.join(cwd, 'gradlew');
   const gradlewExists = await exists(gradlewPath);
   const gradlewExecutable = gradlewExists && (await canExecute(gradlewPath));