content-s3: remove module

Problem: The content-s3 module is largely unused.  It is a headache
maintaining it with little benefit.

Solution: Remove the content-s3 module.  It can be revived in the
future if need be.  Along with the removal of the content-s3 module:

Remove all content-s3 tests in:

t0024-content-s3.t
t2008-althash.t
t3200-instance-restart.t

Remove content-s3 from build matrix.

Remove all libs3 libraries from Dockerfiles.

Author: chu11

.github/workflows/main.yml

@@ -193,12 +193,6 @@ jobs:
         pip3 install --upgrade pip ;
         pip3 install --upgrade --force-reinstall coverage ;
 
-    - name: s3 setup
-      env: ${{matrix.env}}
-      if: matrix.test_s3
-      run: |
-        docker run -d -p 9000:9000 minio/minio server /data; \
-
     - name: generate dumpfile from most recent flux-core tag
       if: (matrix.create_release != true)
       run: |

configure.ac

@@ -450,29 +450,6 @@ AS_IF([test "x$with_flux_security" = "xyes"], [
 ])
 AM_CONDITIONAL([HAVE_FLUX_SECURITY], [test "x$with_flux_security" = "xyes"])
 
-AC_ARG_ENABLE([content-s3],
-    AS_HELP_STRING([--enable-content-s3], [Enable S3 storage backend]))
-
-AS_IF([test "x$enable_content_s3" = "xyes"], [
-    X_AC_CHECK_COND_LIB(s3, S3_initialize)
-    AS_IF([test "x$ac_cv_lib_s3_S3_initialize" != "xyes"], [
-      AC_MSG_ERROR([configured with --enable-content-s3, but libs3 not found])
-    ])
-
-    AC_COMPILE_IFELSE(
-        [AC_LANG_PROGRAM([#include <libs3.h>],
-                         [S3_create_bucket (0,0,0,0,0,0,0,0,0,0,0);])],
-        AC_DEFINE([HAVE_S3_AUTH_REGION], [1], [S3_create_bucket has 11 args]),
-        AC_COMPILE_IFELSE(
-            [AC_LANG_PROGRAM([#include <libs3.h>],
-                             [S3_create_bucket (0,0,0,0,0,0,0,0,0,0,0,0,0);])],
-            AC_DEFINE([HAVE_S3_TIMEOUT_ARG], [1], [S3_create_bucket has 13 args])
-        )
-    )
-])
-
-AM_CONDITIONAL([ENABLE_CONTENT_S3], [test "x$enable_content_s3" = "xyes"])
-
 AC_ARG_ENABLE(
     [broken-locale-mode],
     AS_HELP_STRING([--enable-broken-locale-mode],
@@ -641,7 +618,6 @@ AC_CONFIG_FILES( \
   src/modules/Makefile \
   src/modules/kvs/Makefile \
   src/modules/content-files/Makefile \
-  src/modules/content-s3/Makefile \
   src/modules/job-ingest/Makefile \
   src/modules/job-manager/Makefile \
   src/modules/job-list/Makefile \

src/modules/Makefile.am

@@ -23,10 +23,6 @@ SUBDIRS = \
 	resource \
 	sdbus
 
-if ENABLE_CONTENT_S3
-SUBDIRS += content-s3
-endif
-
 fluxmod_LTLIBRARIES = \
 	barrier.la \
 	connector-local.la \
@@ -48,10 +44,6 @@ fluxmod_LTLIBRARIES = \
 	sdexec.la \
 	sdbus.la
 
-if ENABLE_CONTENT_S3
-fluxmod_LTLIBRARIES += content-s3.la
-endif
-
 # N.B. SOURCES should be empty when module subdir is listed in
 # SUBDIRS above.  This avoids distcheck problems with older automake.
 # Hint: build convenience library in subdir and reference that in LIBADD.
@@ -92,16 +84,6 @@ content_files_la_LIBADD = \
 	$(top_builddir)/src/common/libflux-core.la
 content_files_la_LDFLAGS = $(fluxmod_ldflags) -module
 
-if ENABLE_CONTENT_S3
-content_s3_la_SOURCES =
-content_s3_la_LIBADD = \
-	$(builddir)/content-s3/libcontent-s3.la \
-	$(top_builddir)/src/common/libflux-internal.la \
-	$(top_builddir)/src/common/libflux-core.la \
-	$(LIBS3)
-content_s3_la_LDFLAGS = $(fluxmod_ldflags) -module
-endif
-
 content_sqlite_la_SOURCES = \
         content-sqlite/content-sqlite.c
 content_sqlite_la_CPPFLAGS = \