Fix: usage of postgresql -> postgres for db_type (#10120)

### What problem does this PR solve?

This PR fixes incorrect naming for PostgreSQL usage by replacing all
instances of `postgresql` with the correct `postgres` in the `db_type`
field. This resolves potential configuration errors and ensures
consistency when specifying the database type.

Also fixed handling of None for `get_queue_length`

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

Co-authored-by: cucusenok <BP-116: updated readme.md>

web/src/pages/agent/options.ts

@@ -2133,7 +2133,7 @@ export const QWeatherTimePeriodOptions = [
   '30d',
 ];
 
-export const ExeSQLOptions = ['mysql', 'postgresql', 'mariadb', 'mssql'].map(
+export const ExeSQLOptions = ['mysql', 'postgres', 'mariadb', 'mssql'].map(
   (x) => ({
     label: upperFirst(x),
     value: x,

web/src/pages/data-flow/options.ts

@@ -2133,7 +2133,7 @@ export const QWeatherTimePeriodOptions = [
   '30d',
 ];
 
-export const ExeSQLOptions = ['mysql', 'postgresql', 'mariadb', 'mssql'].map(
+export const ExeSQLOptions = ['mysql', 'postgres', 'mariadb', 'mssql'].map(
   (x) => ({
     label: upperFirst(x),
     value: x,

web/src/pages/flow/constant.tsx

@@ -2911,7 +2911,7 @@ export const QWeatherTimePeriodOptions = [
   '30d',
 ];
 
-export const ExeSQLOptions = ['mysql', 'postgresql', 'mariadb', 'mssql'].map(
+export const ExeSQLOptions = ['mysql', 'postgres', 'mariadb', 'mssql'].map(
   (x) => ({
     label: upperFirst(x),
     value: x,