Bug 26871: Flush SIP2 cache on every SIP request

Bug 26871: Flush SIP2 cache on every SIP request

SIP connections tend to be long lived, weeks if not months, in the
libraries I see. Basically the connection per SIP machine is initiated
once when the SIP machine boots and then never closed until
maintanance needs to be done. Therefore we need to reset the Koha's L1
caches on every SIP request to get the latest sysprefs and configs
from the memcached cache that is shared between all the Koha
programs (intranet, opac, sip, cronjobs) and is guaranteed to be up to
date.

To test:
 0. Have kohadevbox
 1. Enable IssueLog
 2. In one terminal run the command "perl C4/SIP/SIPServer.pm /etc/koha/sites/kohadev/SIPconfig.xml"
 3. Checkin and return a book using telnet:

    $ telnet localhost 6001
    9300CNterm1|COterm1|CPCPL|
    11YN20211010    10565320211010    105653AOCPL|AA1|AB3999900000001|ACterm1|BON|BIN|
    09N20211010    10564420211010    105644APCPL|AOCPL|AB3999900000001|ACterm1|BIN|

 4. Keep the telnet connection open and go to
    http://localhost:8081/cgi-bin/koha/tools/viewlog.pl and check that
    the *checkout* entry is in the circulation rules 5.
 6. Disable IssueLog
 7. Move back to the telnet prompt and check out and return a book again

    11YN20211010    10565320211010    105653AOCPL|AA1|AB3999900000001|ACterm1|BON|BIN|
    09N20211010    10564420211010    105644APCPL|AOCPL|AB3999900000001|ACterm1|BIN|

 8. Go check out the circulation logs and notice a new entry was added
    when it shouldn't have according to the IssueLog syspref!
 9. Apply patch and repeat steps to notice that the syspref is now
    followed correctly.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>