Mark more functions parallel-restricted.
Commit 61c2e1a95f94bb904953a6281ce17a18ac38ee6d allowed parallel
query to be used in more places, revealing via buildfarm member
mandrill that several functions intended to be called from triggers
were incorrectly marked parallel-safe rather than parallel-r
Mark more functions parallel-restricted or parallel-unsafe.
Commit 7aea8e4f2daa4b39ca9d1309a0c4aadb0f7ed81b was overoptimistic
about the degree of safety associated with running various functions
in parallel mode. Functions that take a table name or OID as an
argument are at least parallel-restri
