[frdp] Adds paths for `find` and `ls` for Fuchsia execution. (#26680)

Adds full path for `find` and `ls` commands.

packages/fuchsia_remote_debug_protocol/lib/src/fuchsia_remote_connection.dart

@@ -523,14 +523,15 @@ class FuchsiaRemoteConnection {
   /// found. An exception is thrown in the event of an actual error when
   /// attempting to acquire the ports.
   Future<List<int>> getDeviceServicePorts() async {
-    final List<String> portPaths =
-        await _sshCommandRunner.run('find /hub -name vmservice-port');
+    final List<String> portPaths = await _sshCommandRunner
+        .run('/system/bin/find /hub -name vmservice-port');
     final List<int> ports = <int>[];
     for (String path in portPaths) {
       if (path == '') {
         continue;
       }
-      final List<String> lsOutput = await _sshCommandRunner.run('ls $path');
+      final List<String> lsOutput =
+          await _sshCommandRunner.run('/system/bin/ls $path');
       for (String line in lsOutput) {
         if (line == '') {
           continue;

packages/fuchsia_remote_debug_protocol/test/fuchsia_remote_connection_test.dart

@@ -21,10 +21,12 @@ void main() {
     setUp(() {
       mockRunner = MockSshCommandRunner();
       // Adds some extra junk to make sure the strings will be cleaned up.
-      when(mockRunner.run(argThat(startsWith('find')))).thenAnswer((_) =>
-          Future<List<String>>.value(<String>['/hub/blah/blah/blah/vmservice-port\n']));
-      when(mockRunner.run(argThat(startsWith('ls')))).thenAnswer((_) =>
-          Future<List<String>>.value(<String>['123\n\n\n', '456  ', '789']));
+      when(mockRunner.run(argThat(startsWith('/system/bin/find')))).thenAnswer(
+          (_) => Future<List<String>>.value(
+              <String>['/hub/blah/blah/blah/vmservice-port\n']));
+      when(mockRunner.run(argThat(startsWith('/system/bin/ls')))).thenAnswer(
+          (_) => Future<List<String>>.value(
+              <String>['123\n\n\n', '456  ', '789']));
       const String address = 'fe80::8eae:4cff:fef4:9247';
       const String interface = 'eno1';
       when(mockRunner.address).thenReturn(address);