**What happened:**

My password for external Postgres RDS contained '@123' at the end which got appended to the host of the DB due to some bug. One can notice in the logs, the DB_HOST has an unwanted 123@ in the front of it  DB_HOST=**123@**{{postgres_host}}. I removed '@' character from the password and it worked fine. 

I am using the latest image of apache/airflow and using the official helm chart.

```
kc logs airflow-run-airflow-migrations-xxx
BACKEND=postgresql
DB_HOST=123@{{postgres_host}}
DB_PORT=5432
....................
ERROR! Maximum number of retries (20) reached.

Last check result:
$ run_nc '123@{{postgres_host}}' '5432'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
socket.gaierror: [Errno -2] Name or service not known
Can't parse  as an IP address
```

**Steps to reproduce:**
One can easily reproduce this by using a password that contains the '@' character in it.
```
data:
  metadataConnection:
    user: {{postgres_airflow_username}}
    pass: {{postgres_airflow_password}}
    protocol: postgresql  
    host: {{postgres_host}}
    port: 5432
    db: {{postgres_airflow_dbname}}
```

**Expected behavior:**
Migrations should run irrespective if the Postgres password contains an @ character or not.
chart/tests/test_metadata_connection_secret.py
#
#
import base64
import unittest
import jmespath
from tests.helm_template_generator import render_chart
class MetadataConnectionSecretTest(unittest.TestCase):
    non_chart_database_values = {
        "user": "someuser",
        "pass": "somepass",
        "host": "somehost",
        "port": 7777,
        "db": "somedb",
    }
    def test_should_not_generate_a_document_if_using_existing_secret(self):
        docs = render_chart(
            values={"data": {"metadataSecretName": "foo"}},
            show_only=["templates/secrets/metadata-connection-secret.yaml"],
        )
        assert 0 == len(docs)
    def _get_connection(self, values: dict) -> str:
        docs = render_chart(
            values=values,
            show_only=["templates/secrets/metadata-connection-secret.yaml"],
        )
        encoded_connection = jmespath.search("data.connection", docs[0])
        return base64.b64decode(encoded_connection).decode()
    def test_default_connection(self):