fix(Baserow): Fix DATABASE_HOST env var (#8872)

**Description**
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As it was, baserow container would throw an error:
```could not translate host name "postgresql://baserow:B7CSHtfAnVI27t6wCpoCgJTEaC3gIjUB1jrjuXgruosEubgxhTAtypPPA8Wlvm@baserow-cnpg-main-rw:5432/baserow" to address: Name or service not known```
I looked at the documentation and found it just wants the host there, not a full postgresql connection string.
Tried the change from this PR on my TN Scale test VM with `edit deploy`, and it worked.
⚒️ Fixes  # <!--(issue)-->

**⚙️ Type of change**

- [ ] ⚙️ Feature/App addition
- [x] 🪛 Bugfix
- [ ] ⚠️ Breaking change (fix or feature that would cause existing functionality to not work as expected)
- [ ] 🔃 Refactor of current code

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Co-authored-by: Stavros kois <s.kois@outlook.com>
Co-authored-by: Stavros Kois <47820033+stavros-k@users.noreply.github.com>

charts/stable/baserow/values.yaml

@@ -50,7 +50,7 @@ workload:
             DATABASE_HOST:
               secretKeyRef:
                 name: cnpg-main-urls
-                key: std
+                key: host
             DATABASE_PASSWORD:
               secretKeyRef:
                 name: cnpg-main-user