[yugabyte#7014]: Fix backup unit tests.

Summary: Commit yugabyte@335b3d9 and https://github.com/yugabyte/yugabyte-db/issues/3579c17b017f39f59f56a9c099baf16a4bf2326b broke the unit tests for backup. This diff addresses those issues.

Test Plan:
ybd --cxx-test tools_yb-backup-test_ent
ybd --java-test org.yb.cql.TestYbBackup
ybd --java-test org.yb.pgsql.TestYbBackup
Jenkins

Reviewers: sanketh, oleg

Reviewed By: oleg

Subscribers: jenkins-bot, ybase

Differential Revision: https://phabricator.dev.yugabyte.com/D10478

ent/src/yb/tools/yb-backup-test_ent.cc

@@ -54,6 +54,10 @@ class YBBackupTest : public pgwrapper::PgCommandTestBase {
       tmp_dir_ = JoinPathSegments(
         tmp_dir_, string(CURRENT_TEST_CASE_NAME()) + '_' + RandomHumanReadableString(8));
     }
+    // Create the directory if it doesn't exist.
+    if (!Env::Default()->DirExists(tmp_dir_)) {
+      EXPECT_OK(Env::Default()->CreateDir(tmp_dir_));
+    }
 
     return JoinPathSegments(tmp_dir_, subdir);
   }
@@ -69,6 +73,7 @@ class YBBackupTest : public pgwrapper::PgCommandTestBase {
             << " --ysql_host=" << pg_hp.host()
             << " --ysql_port=" << pg_hp.port()
             << " --storage_type nfs"
+            << " --nfs_storage_path " << tmp_dir_
             << " --no_ssh"
             << " --no_auto_name";
 #if defined(__APPLE__)

java/yb-client/src/test/java/org/yb/util/YBBackupUtil.java

@@ -95,6 +95,7 @@ public static String runYbBackup(List<String> args) throws Exception {
         "--remote_ysql_dump_binary=" + ysqlDumpPath,
         "--remote_ysql_shell_binary=" + ysqlShellPath,
         "--storage_type", "nfs",
+        "--nfs_storage_path", TestUtils.getBaseTmpDir(),
         "--no_ssh",
         "--no_auto_name"));
 

managed/devops/bin/yb_backup.py

@@ -1183,7 +1183,7 @@ def run_ssh_cmd(self, cmd, server_ip, upload_cloud_cfg=True, num_ssh_retry=3, en
                 'cd / && %s bash -c ' % (change_user_cmd) + pipes.quote(cmd)],
                 num_retry=num_retries)
         else:
-            return self.run_program(['bash', '-c', pipes.quote(cmd)])
+            return self.run_program(['bash', '-c', cmd])
 
     def find_data_dirs(self, tserver_ip):
         """
@@ -1653,11 +1653,11 @@ def find_nfs_storage(self, tserver_ip):
         :param tserver_ip: tablet server ip
         """
         try:
-            self.run_ssh_cmd(['find', self.args.nfs_storage_path], tserver_ip)
+            self.run_ssh_cmd(['ls', self.args.nfs_storage_path], tserver_ip)
         except Exception as ex:
             raise BackupException(
                 ('Did not find nfs backup storage path: %s mounted on tablet server %s'
-                % (self.args.nfs_storage_path, tserver_ip)))
+                 % (self.args.nfs_storage_path, tserver_ip)))
 
     def upload_metadata_and_checksum(self, src_path, dest_path):
         """