Old transactions not visible in block explorer

[onetwothree-mar]

Describe the bug
Block explorer does not show transactions that are too old.
A user reported that there were no transactions visible on https://explorer.dusk.network/transactions/

As the network was not completely reset recently, there should have been a fair amount of transactions that were added a few weeks ago but where not visible on the blockexplorer.

Spamming some new transactions lead to the new transactions being shown in the block explorer; however older transactions were still not shown even after scrolling down until the end.

To Reproduce
Wait for a few weeks until the newly generated transactions don't show up anymore?

Expected behaviour
Recent transactions under https://explorer.dusk.network/ showing the most recent transactions, even if those happened a long time ago & being able to scroll down the full history of transactions in https://explorer.dusk.network/transactions/.

Logs/Screenshot

Platform
Fill as appropriate

• Architecture: ARM
• OS: MacOS
• Browser Chrome

[goshawk-3]

The observed effect is a result of implementing #1400 (respectively PR #1401). In short, Recent Transactions view visualizes transactions from last 10 000 blocks only.

This may be improved in near future by caching Recent Transactions data in block explorer back-end.

FYI @kieranhall