fix: Only set valid timezone values

[come-nc]

No description provided.

[come-nc]

/backport to stable33

[come-nc]

/backport to stable32

[come-nc]

/backport to stable31

[backportbot]

The backport to stable31 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable31
git pull origin stable31

# Create the new backport branch
git checkout -b backport/1049/stable31

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 1d7de7bc

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/1049/stable31

Error: Failed to clone repository: Failed to create working tree: Preparing worktree (new branch 'backport/1049/stable31')
fatal: not a valid object name: 'origin/stable31'

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[backportbot]

The backport to stable32 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable32
git pull origin stable32

# Create the new backport branch
git checkout -b backport/1049/stable32

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 1d7de7bc

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/1049/stable32

Error: Failed to clone repository: Failed to create working tree: Preparing worktree (new branch 'backport/1049/stable32')
fatal: not a valid object name: 'origin/stable32'

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[backportbot]

The backport to stable33 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable33
git pull origin stable33

# Create the new backport branch
git checkout -b backport/1049/stable33

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 1d7de7bc

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/1049/stable33

Error: Failed to clone repository: Failed to create working tree: Preparing worktree (new branch 'backport/1049/stable33')
fatal: not a valid object name: 'origin/stable33'

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[come-nc]

No backports needed, master branch supports 30 to 33.