FINERACT-2269: various small dev-focused improvements

remove unnecessary javadoc html5 option

html5 output is the default since at least Java 17

improve markdown formatting for PR template

fix casing, per GH recommendations

https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/creating-a-pull-request-template-for-your-repository recommends lowercase

document system default Java issues

reorder integration test hints importance-wise

make devRun the default

It's faster and more obviously useful for developers.

See https://lists.apache.org/thread/zxvtx9nqqbojvt0dd65tk8zd4xp6ot0t

mention gradle not re-running tests

remove Gitpod

per James, Ádám, and Victor, this is no longer used/supported

for setting up a local dev environment see the top-level README.md and https://fineract-academy.com

fineract-war/build.gradle

@@ -145,7 +145,7 @@ distributions {
             from("$rootDir/") {
                 exclude '**/build' , '.git', '**/.gradle', '.github', '**/.settings', '**/.project', 
                         '**/.classpath', '.idea', 'out', '._.DS_Store', '.DS_Store', 'WebContent', 
-                        '**/.externalToolbuilders', '.theia', '.gitpod.yml', 'LICENSE_RELEASE', 
+                        '**/.externalToolbuilders', '.theia', 'LICENSE_RELEASE', 
                         'NOTICE_RELEASE', '**/licenses', '*.class', '**/bin', '*.log', '.dockerignore', 
                         '**/.gitkeep'