Respect original content when creating secrets (#24745) (#24746)

Backport #24745 by @wolfogre

Fix #24721.

Follow what GitHub does:
- Don't trim spaces for secrets.
- Newline should be `\n` instead of `\r\n`.

Did some tests with:

```yaml
name: secrets
on: push
jobs:
  show_secrets:
    runs-on: ubuntu-latest
    steps:
      - name: Dump secrets context
        run: echo '${{ toJSON(secrets) }}' | base64
```

`AAAAAA`:
```text
   AAAAAA
AAAAAA

```
`BBBBBB`:
```text

BBBBBB
BBBBBB
```

On GitHub:

<img width="675" alt="image"
src="https://github.com/go-gitea/gitea/assets/9418365/0ec60652-c2a3-47bb-9f9d-7e81665355a8">

On Gitea (before):

<img width="673" alt="image"
src="https://github.com/go-gitea/gitea/assets/9418365/cce818bf-5edc-4656-86e1-2c81c304cdb2">

On Gitea (after):

<img width="673" alt="image"
src="https://github.com/go-gitea/gitea/assets/9418365/0b3b15af-4d48-4bab-a334-4738a1b0eb4a">

Co-authored-by: Jason Song <i@wolfogre.com>
(cherry picked from commit e4f200e616)

models/secret/secret.go

@@ -59,7 +59,7 @@ func newSecret(ownerID, repoID int64, name, data string) *Secret {
 
 // InsertEncryptedSecret Creates, encrypts, and validates a new secret with yet unencrypted data and insert into database
 func InsertEncryptedSecret(ctx context.Context, ownerID, repoID int64, name, data string) (*Secret, error) {
-	encrypted, err := secret_module.EncryptSecret(setting.SecretKey, strings.TrimSpace(data))
+	encrypted, err := secret_module.EncryptSecret(setting.SecretKey, data)
 	if err != nil {
 		return nil, err
 	}