[Fleet] Fix preconfiguration inputs enablement (#126205) (#126246)

(cherry picked from commit b1444ca)

Co-authored-by: Nicolas Chaulet <nicolas.chaulet@elastic.co>

x-pack/plugins/fleet/server/services/package_policy.test.ts

@@ -1654,8 +1654,8 @@ describe('Package policy service', () => {
       });
     });
 
-    describe('when an input or stream is disabled on the original policy object', () => {
-      it('remains disabled on the resulting policy object', () => {
+    describe('when an input or stream is disabled by default in the package', () => {
+      it('allow preconfiguration to enable it', () => {
         const basePackagePolicy: NewPackagePolicy = {
           name: 'base-package-policy',
           description: 'Base Package Policy',
@@ -1864,13 +1864,13 @@ describe('Package policy service', () => {
         expect(template2Inputs).toHaveLength(1);
 
         const logsInput = template1Inputs?.find((input) => input.type === 'logs');
-        expect(logsInput?.enabled).toBe(false);
+        expect(logsInput?.enabled).toBe(true);
 
         const logfileStream = logsInput?.streams.find(
           (stream) => stream.data_stream.type === 'logfile'
         );
 
-        expect(logfileStream?.enabled).toBe(false);
+        expect(logfileStream?.enabled).toBe(true);
       });
     });
 

x-pack/plugins/fleet/server/services/package_policy.ts

@@ -1292,14 +1292,11 @@ export function preconfigurePackageInputs(
       continue;
     }
 
-    // For flags like this, we only want to override the original value if it was set
-    // as `undefined` in the original object. An explicit true/false value should be
-    // persisted from the original object to the result after the override process is complete.
-    if (originalInput.enabled === undefined && preconfiguredInput.enabled !== undefined) {
+    if (preconfiguredInput.enabled !== undefined) {
       originalInput.enabled = preconfiguredInput.enabled;
     }
 
-    if (originalInput.keep_enabled === undefined && preconfiguredInput.keep_enabled !== undefined) {
+    if (preconfiguredInput.keep_enabled !== undefined) {
       originalInput.keep_enabled = preconfiguredInput.keep_enabled;
     }
 
@@ -1322,7 +1319,7 @@ export function preconfigurePackageInputs(
           continue;
         }
 
-        if (originalStream?.enabled === undefined) {
+        if (stream.enabled !== undefined) {
           originalStream.enabled = stream.enabled;
         }