Rename the beatname.sh script to beatname (elastic#4933)

This makes it a bit less weird when using the commands on Debian/Centos systems.

CHANGELOG.asciidoc

@@ -16,6 +16,7 @@ https://github.com/elastic/beats/compare/v6.0.0-beta1...master[Check the HEAD di
 
 - The log directory (`path.log`) for Windows services is now set to `C:\ProgramData\[beatname]\logs`. {issue}4764[4764]
 - Fail if removed setting output.X.flush_interval is explicitly configured.
+- Rename the `/usr/bin/beatname.sh` script (e.g. `metricbeat.sh`) to `/usr/bin/beatname`. {pull}4933[4933]
 
 *Auditbeat*
 
@@ -89,7 +90,7 @@ https://github.com/elastic/beats/compare/v6.0.0-beta1...master[Check the HEAD di
 - Make config object public for graphite and http server {pull}4820[4820]
 - Add system uptime metricset. {issue}[4848[4848]
 - Add `filesystem.ignore_types` to system module for ignoring filesystem types. {issue}4685[4685]
- 
+
 *Packetbeat*
 
 *Winlogbeat*

dev-tools/packer/platforms/centos/run.sh.j2

@@ -33,7 +33,7 @@ FPM_ARGS=(
         --after-install /tmp/systemd-daemon-reload.sh
         --config-files /etc/{{.beat_name}}/{{.beat_name}}.yml
         homedir/=/usr/share/{{.beat_name}}
-        beatname-${RUNID}.sh=/usr/bin/{{.beat_name}}.sh
+        beatname-${RUNID}.sh=/usr/bin/{{.beat_name}}
         {{.beat_name}}-linux-{{.arch}}=/usr/share/{{.beat_name}}/bin/{{.beat_name}}
         {{.beat_name}}-linux.yml=/etc/{{.beat_name}}/{{.beat_name}}.yml
         {{.beat_name}}-linux.reference.yml=/etc/{{.beat_name}}/{{.beat_name}}.reference.yml

dev-tools/packer/platforms/debian/run.sh.j2

@@ -30,7 +30,7 @@ FPM_ARGS=(
         --after-install /tmp/systemd-daemon-reload.sh
         --config-files /etc/{{.beat_name}}/{{.beat_name}}.yml
         homedir/=/usr/share/{{.beat_name}}
-        beatname-${RUNID}.sh=/usr/bin/{{.beat_name}}.sh
+        beatname-${RUNID}.sh=/usr/bin/{{.beat_name}}
         {{.beat_name}}-linux-{{.arch}}=/usr/share/{{.beat_name}}/bin/{{.beat_name}}
         {{.beat_name}}-linux.yml=/etc/{{.beat_name}}/{{.beat_name}}.yml
         {{.beat_name}}-linux.reference.yml=/etc/{{.beat_name}}/{{.beat_name}}.reference.yml