chore: Add Postgres bin to PATH (#34265)

Instead of using absolute paths to Postgres binaries, and in doing so,
hard-coding the Postgres version number, we add the bin folder to `PATH`
so they're available directly.

This also won't need the `current` symlink we created. That symlink is
causing problems in some post-installations scripts in `apt`/`dpkg`,
since they're expecting a _number_ in that folder, and sees `current`,
it's confused and produces this error:

```
dpkg: warning: version 'current' has bad syntax: version number does not start with digit
```

After this is merged, we should be able to get rid of the `current`
symlink as well.

**/test sanity**

<!-- This is an auto-generated comment: Cypress test results  -->
> [!TIP]
> 🟢 🟢 🟢 All cypress tests have passed! 🎉 🎉 🎉
> Workflow run:
<https://github.com/appsmithorg/appsmith/actions/runs/9541787920>
> Commit: 1012266e0924248b0f13a91bee464303e86b87a6
> <a
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target="_blank">Cypress dashboard</a>.
> Tags: `@tag.Sanity`

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<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Chores**
- Updated Docker configurations to streamline PostgreSQL 13 integration.
- Simplified PostgreSQL commands in scripts by removing explicit
versioning paths.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

deploy/docker/base.dockerfile

@@ -32,6 +32,8 @@ RUN set -o xtrace \
   && ln -s /usr/lib/postgresql/13 /usr/lib/postgresql/current \
   && apt-get clean
 
+ENV PATH="/usr/lib/postgresql/13/bin:${PATH}"
+
 # Install Java
 RUN set -o xtrace \
   && mkdir -p /opt/java \

deploy/docker/fs/opt/appsmith/entrypoint.sh

@@ -4,6 +4,9 @@ set -e
 
 tlog "Running as: $(id)"
 
+# Temporary, remove after this change goes into `base.dockerfile`.
+export PATH="/usr/lib/postgresql/13/bin:${PATH}"
+
 stacks_path=/appsmith-stacks
 
 export SUPERVISORD_CONF_TARGET="$TMP/supervisor-conf.d/"  # export for use in supervisord.conf
@@ -427,7 +430,7 @@ init_postgres() {
 
     if [[ ! -e "$POSTGRES_DB_PATH/PG_VERSION" ]]; then
       tlog "Initializing local Postgres data folder"
-      su postgres -c "/usr/lib/postgresql/13/bin/initdb -D $POSTGRES_DB_PATH"
+      su postgres -c "initdb -D $POSTGRES_DB_PATH"
     fi
   else
     runEmbeddedPostgres=0

deploy/docker/fs/opt/appsmith/run-postgres.sh

@@ -1,4 +1,4 @@
 #!/bin/bash
 
 rm -f /appsmith-stacks/data/postgres/main/core.*
-exec /usr/lib/postgresql/13/bin/postgres -D "/appsmith-stacks/data/postgres/main" -c listen_addresses=127.0.0.1
+exec postgres -D "/appsmith-stacks/data/postgres/main" -c listen_addresses=127.0.0.1