This PR fixes the bug reported in #33365.
The impact of the bug is not catastrophic. After a transaction is
ultimately fetched, validation and propagation will be performed based
on the fetched body, and any response with a mismatched type is treated
as a protocol violation. An attacker could only waste the limited
portion of victim’s bandwidth at most.
However, the reasons for submitting this PR are as follows
1. Fetching a transaction announced with an arbitrary type is a weird
behavior.
2. It aligns with efforts such as EIP-8077 and #33119 to make the
fetcher smarter and reduce bandwidth waste.
Regarding the `FilterType` function, it could potentially be implemented
by modifying the Filter function's parameter itself, but I wasn’t sure
whether changing that function is acceptable, so I left it as is.
56d201b0fe