[BACKPORT 2024.1][#21947] YSQL: fix postgres process crash on "show a…

…ll" command

Summary:
To reproduce this bug:

```
./bin/ysqlsh -c "show all"
server closed the connection unexpectedly
        This probably means the server terminated abnormally
        before or while processing the request.
connection to server was lost
```

The reason is that a GUC variable must have a non-NULL short_desc that the "show
all" command needs to access. When I added the new GUC
`yb_enable_ddl_atomicity_infra` in commit
6091cc8, I added the text description to
long_desc when it should be short_desc. Fixed by swapping them.
Jira: DB-10864

Original commit: 7036256 / D34147

Test Plan:
(1) Manual test, `show all` now works

./bin/ysqlsh -c "show all"

(2) Run the original benchbase test in the issue and it now passes
1. Start a local RF-3 cluster
   ./bin/yb-ctl create --rf 3
2. Build benchbase.jar
export JAVA_HOME=/opt/jdk-17
export PATH=$PATH:$JAVA_HOME/bin
cd $HOME/code
rm -rf benchbase
git clone https://github.com/yugabyte/benchbase.git
cd benchbase
./mvnw clean package -P yugabyte -DskipTests
cd target
tar xvzf benchbase-yugabyte.tgz
cd benchbase-yugabyte/
3. Run the test command and see no PG process crash.
/opt/jdk-17/bin/java -Xmx8g -jar benchbase.jar -b voter -c config/yugabyte/sample_voter_config.xml --create=true --load=true --execute=true --params endpoint=127.0.0.1 -im 5000 2>&1

Reviewers: fizaa, smishra

Reviewed By: smishra

Subscribers: yql

Tags: #jenkins-ready

Differential Revision: https://phorge.dev.yugabyte.com/D34185

src/postgres/src/backend/utils/misc/guc.c

@@ -2484,9 +2484,9 @@ static struct config_bool ConfigureNamesBool[] =
 
 	{
 		{"yb_enable_ddl_atomicity_infra", PGC_SUSET, DEVELOPER_OPTIONS,
-			NULL,
 			gettext_noop("Used along side with yb_ddl_rollback_enabled to control "
 						 "whether DDL atomicity is enabled."),
+			NULL,
 			GUC_NOT_IN_SAMPLE
 		},
 		&yb_enable_ddl_atomicity_infra,