/bin/true if you're a positive person) is a real shell - it's just not an interactive shell :-) There's also
/sbin/nologin on some systems which serves the same purpose.
As to whether your Apache user needs an interactive shell (something like
bash), the answer as others have said is "Usually, no."
Setting the Apache user's shell to something non-interactive is generally good security practice (really all service users who don't have to log in interactively should have their shell set to something that's non-interactive).
Tor an existing environment like yours try it and see if anything breaks.
If nothing breaks use the non-interactive shell from now on.
If stuff breaks try to fix it without restoring the interactive shell :-)