Hi @appsmithorg/contributor-support, @rohan-arthur, @nidhi-nair
Fixes#19723
**What’s in this PR:**
1. In Postgres Plugin:
- Added two imports: PSQLException and PSQLState to identify the type of
exception and state of error.
- Added a condition to validate the empty port field.
- Removed the default port when the port is empty.
- Removed “Failed to initialize pool:” term in the error message.
2. In PostgresErrorMessages
- Added two constant value for Missing port and invalid host and port.
3. In PostgresPluginTest
- Added a test case to validate the missing port error message.
**Screenshots :**
1. If any of the field like host address, port, DB name etc is wrong -
There is a term in the error message along with the error message in the
toast "Failed to initialize pool: ". This is not required. - Fixed

2. If host address or port is wrong, there is no reference of that in
the error message. - Fixed

3. There is no error message when the port number is left empty. - Fixed

**Test cases :**

**Why I didn’t provide test cases for invalid host and port :**
Those errors are triggered by the createConnectionPool method, which is
private, so we can’t access it in the test file.
<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit
- **New Features**
- Improved validation for PostgreSQL datasource configurations, ensuring
that a port is specified.
- Enhanced error messaging for connection issues related to missing or
invalid port and hostname.
- **Bug Fixes**
- Refined error handling during connection pool initialization for
clearer feedback on specific connection issues.
- **Tests**
- Added a test to validate behavior when the datasource configuration
has an empty port, improving coverage for validation logic.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->