Intern IndexFieldCapabilities Type String on Read (#76405) #77754
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In case of handling a large number of these messages, i.e. when fetching field caps
for many indices (and/or those indices contain lots of fields) the type string is repeated
many times over. As these strings are already interned because they are constants, taking
the performance hit of interning them on deserialization seems a reasonable trade-off
for the benefit of saving a non-trivial amount of memory for large clusters as well as
speeding up
org.elasticsearch.action.fieldcaps.TransportFieldCapabilitiesAction#merge
which uses these strings in map lookup and will run significantly faster with interned strings
instead of fresh strings that do not have their hash values cached yet.
backport of #76405