Prevent duplicates by cleaning up HTML tags with timestamps or tokens

[grossir]

We have seen this in coloctapp, which uses a vlex backend #1215 . There, some <img> tags had AWS tokens that changed each time

I have a new example in the older files (from before July 2012) for scctapp_u, which have a timestamped <script> tag from "Incapsula"
Open this example a few seconds apart and this tag will change:
<script type="text/javascript" src="/_Incapsula_Resource?SWJIYLWA=719d34d31c8e3a6e6fffd425f7e032f3&ns=1&cb=1672922138" async></script>

So we could define a default cleaning step for HTML files that tries to remove elements that may hold tokens or timestamps.

Additionally, we could compute the hash in Juriscraper, so that one can inspect if this changes in development