Memory leak when parsing broken microdescriptors
When we're parsing microdescriptors, we don't clear the dynamically allocated part of the tokens after parsing. This can leak memory if the microdescriptors are badly formed.
This can enable a comparatively slow denial of service (on the order of several MB per MD download request made to a hostile source), and needs to be patched.
Found as a needle in the haystack of #11618 (moved).