Valid start time offset not working properly in tx group

[yiliev0]

Description

When creating a transaction group, users can set a valid start time for all transactions. However, if the valid start time is adjusted forward (e.g., by 5-10 minutes), the system only applies a one-minute offset rather than the full specified duration.

Steps to reproduce

1. Create a new transaction group.
2. Set a valid start time for the group.
3. Attempt to move the valid start time forward by a specific amount (e.g., 5-10 minutes).
4. Click on Create and share button
5. Observe that the valid start time in the transaction only advances by one minute.

Additional context

Expected Behavior:
The valid start time should update according to the full time offset selected by the user (e.g., moving forward by 5 minutes should result in a 5-minute offset).

Actual Behavior:
The system only applies a one-minute increment regardless of the selected time offset.

Hedera network

No response

Version

0.9.0

Operating system

None