Update BountyDepositBase on Asset Hub Polkadot and Kusama

[dhirajs0]

Summary

Update the BountyDepositBase parameter for pallet_bounties on both Asset Hub Polkadot and Asset Hub Kusama to use explicit currency values that better reflect the economic significance of a bounty proposal.

• Asset Hub Polkadot: system_para_deposit(0, 176) -> 10 * DOLLARS (10 DOT)
• Asset Hub Kusama: system_para_deposit(0, 176) -> 10 * QUID (~0.33 KSM)

Motivation

The previous deposit was derived from system_para_deposit(0, 176), which only accounted for byte-level storage cost and passed 0 for the items parameter. Since bounty proposals are significant governance actions that request treasury funds, the deposit should reflect that weight -- similar to how SubmissionDeposit for referenda is set to a meaningful fixed value (10 DOT) rather than being purely storage-derived.

Setting BountyDepositBase to a fixed value aligns with the pattern used by other governance deposits on Asset Hub and ensures the deposit is proportional to the action being taken. The deposit is fully returned to the proposer when the bounty is approved, so legitimate users are not penalized.

Context

• Bounty proposals are permissionless -- any signed account can submit them.
• The deposit is slashable on rejection (close_bounty by RejectOrigin slashes the bond into Treasury).
• The deposit is returned in full when the bounty is approved and funded.
• Other governance deposits on Asset Hub use fixed values (e.g., SubmissionDeposit = 10 * DOLLARS for referenda), so this change follows the same convention.

[dhirajs0]

Closing this PR as I have raised another PR here: #1134 to the 2603 release branch( oty-2603)