Travis-CI: Optimize rate of false negatives vs true failures

Move 'encryption' tests to another job, since the 'binlog' and 'rpl'
tests are so slow and often make the job timeout (after 50 minutes).

Allow failure in ppc64el as it frequently fails due to out-of-memory.
A simple restart often fixes it, but we can't depend on restarts.

Also re-enable arm64 as MDEV-23955 is now fixed.

MERGING: This commit is OK to merge 10.6 and upwards.

.travis.yml

@@ -114,8 +114,8 @@ compiler:
   - clang
 env:
   - CC_VERSION=7 TYPE=RelWithDebInfo MYSQL_TEST_SUITES=archive,optimizer_unfixed_bugs,parts,sys_vars,unit,vcol,innodb,innodb_gis,innodb_zip,innodb_fts
-  - CC_VERSION=7 TYPE=RelWithDebInfo MYSQL_TEST_SUITES=binlog,binlog_encryption,encryption,rocksdb,versioning,rpl
-  - CC_VERSION=7 TYPE=RelWithDebInfo MYSQL_TEST_SUITES=csv,federated,funcs_1,funcs_2,gcol,handler,heap,json,maria,perfschema,plugins,multi_source,roles
+  - CC_VERSION=7 TYPE=RelWithDebInfo MYSQL_TEST_SUITES=binlog,binlog_encryption,rocksdb,versioning,rpl
+  - CC_VERSION=7 TYPE=RelWithDebInfo MYSQL_TEST_SUITES=csv,federated,funcs_1,funcs_2,gcol,handler,heap,json,maria,perfschema,plugins,multi_source,roles,encryption
   - CC_VERSION=10 TYPE=RelWithDebInfo MYSQL_TEST_SUITES=main
 
 jobs:
@@ -191,10 +191,10 @@ jobs:
       arch: s390x
       compiler: gcc
       env: CC_VERSION=10 TYPE=RelWithDebInfo MYSQL_TEST_SUITES=main
-    # Sporadically fails on main.multi_update_big test (MDEV-23955)
-    - arch: arm64
     # Until OSX becomes a bit more stable
     - os: osx
+    # ppc64el builder frequently runs out of memory
+    - arch: ppc64le
 
 before_install:
   - if [[ "${TRAVIS_OS_NAME}" == 'osx' ]]; then