[TESTNET BUG] reward_slot_holders endpoint isn't always showing the correct address

## Describe the bug

Since the Bitcoin chain behind Testnet is regtest, some of the addresses on the `reward_slot_holders` page are not in the correct format (i.e. they are testnet addresses instead of regtest ones, even if the node processes them as regtest addresses).

## Steps To Reproduce

For example, at block [54053](https://mempool.bitcoin.regtest.hiro.so/block/5d1adaf430f5f8553c49cf96171acd7934021025f067c7006bc675541344b34d), the 2 rewarded addresses according to the [bitcoin chain](https://mempool.bitcoin.regtest.hiro.so/tx/0be05f8677131a0b91a9d38b132ed8e3324e9041969c42ee942e690e4eb6becc) were:
- `mgZ5KJFnXmSvdrPNR7eQGz2RUKeqBanpAM`
- `bcrt1qxnzlc57krja4jzq6vq3fylll0rydxr2xst4erg`

However, the [reward_slot_holders](https://api.testnet.hiro.so/extended/v1/burnchain/reward_slot_holders?limit=250&offset=200) endpoint shows one of the addresses as a testnet one (`tb1qxnzlc57krja4jzq6vq3fylll0rydxr2xjzv55p`):


Going to the individual `reward_slot_holders` for each address:
- [mgZ5KJFnXmSvdrPNR7eQGz2RUKeqBanpAM](https://api.testnet.hiro.so/extended/v1/burnchain/reward_slot_holders/mgZ5KJFnXmSvdrPNR7eQGz2RUKeqBanpAM) - is being shown right
- [tb1qxnzlc57krja4jzq6vq3fylll0rydxr2xjzv55p](https://api.testnet.hiro.so/extended/v1/burnchain/reward_slot_holders/tb1qxnzlc57krja4jzq6vq3fylll0rydxr2xjzv55p) - the address does not exist on the bitcoin chain, however the reward slots received by `bcrt1qxnzlc57krja4jzq6vq3fylll0rydxr2xst4erg` appear here
- [bcrt1qxnzlc57krja4jzq6vq3fylll0rydxr2xst4erg](https://api.testnet.hiro.so/extended/v1/burnchain/reward_slot_holders/bcrt1qxnzlc57krja4jzq6vq3fylll0rydxr2xst4erg) - no reward slots shown, even though they were received

This example is relevant because `tb1qxnzlc57krja4jzq6vq3fylll0rydxr2xjzv55p` and `bcrt1qxnzlc57krja4jzq6vq3fylll0rydxr2xst4erg` contain the same version and hashbytes, but the first is on testnet while the last one is on regtest.

## Expected behavior

The reward slot holders endpoint should show the slots received by `tb1qxnzlc57krja4jzq6vq3fylll0rydxr2xjzv55p` under the `bcrt1qxnzlc57krja4jzq6vq3fylll0rydxr2xst4erg` address instead.

## Environment

Hosted API (https://api.testnet.hiro.so) and hosted bitcoin explorer (https://mempool.bitcoin.regtest.hiro.so)

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### Minor, Non-launch blocking bugs
**Minor bugs**
- [x] Bugs in non-critical software (CLI, UI, etc) that doesn’t impact critical functionality