install.sh: address shellcheck warnings

Replace legacy shell test operator (-o) with more portable OR (||) syntax.
Fix fragile file handling in find loop by using while read loop instead.

Warnings fixed:
- SC2166: Replace [ p -o q ] with [ p ] || [ q ]
- SC2044: Replace for loop over find with while read loop

While no issues were observed with the current code, these changes improve
robustness and portability across different shell environments.

also, set the pipefail option, so that we can catch the unexpected
failure of `find` command call.

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#22385

install.sh

@@ -7,7 +7,7 @@
 # SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
 #
 
-set -e
+set -eo pipefail
 
 if [ -z "$BASH_VERSION" ]; then
     echo "Unsupported shell, please run this script on bash."
@@ -227,18 +227,17 @@ check_usermode_support() {
 . /etc/os-release
 
 is_redhat_variant() {
-    is_redhat=0
+    local is_redhat=0
     for i in $ID $ID_LIKE; do
-        if [ "$i" = "rhel" -o "$i" = "fedora" -o "$i" = "centos" ]; then
-            is_redhat=1
-            break
-        fi
+        case "$i" in
+          rhel|fedora|centos) is_redhat=1;;
+        esac
     done
     [ $is_redhat -eq 1 ]
 }
 
 is_debian_variant() {
-    [ "$ID_LIKE" = "debian" -o "$ID" = "debian" ]
+    [ "$ID_LIKE" = "debian" ] || [ "$ID" = "debian" ]
 }
 
 is_alpine() {
@@ -443,7 +442,7 @@ if ! $without_systemd; then
 fi
 install -m755 seastar/scripts/seastar-cpu-map.sh -Dt "$rprefix"/scripts
 install -m755 seastar/dpdk/usertools/dpdk-devbind.py -Dt "$rprefix"/scripts
-for i in $(find libreloc/ -maxdepth 1 -type f); do
+find libreloc/ -maxdepth 1 -type f | while read -r i; do
     install -m755 "$i" -Dt "$rprefix/libreloc"
 done
 for i in $(find libreloc/fipscheck/ -maxdepth 1 -type f); do