[Proguard] Fix file location, make it more aggressive and remove deprecated option

Took 3 hours 45 minutes

android/app/build.gradle

@@ -73,7 +73,6 @@ android {
         release {
             signingConfig signingConfigs.release
             minifyEnabled true
-            useProguard true
 
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
         }

android/app/proguard-rules.pro

@@ -1,3 +1,4 @@
+-optimizationpasses 5
 ## Flutter wrapper
 -keep class io.flutter.app.** { *; }
 -keep class io.flutter.plugin.**  { *; }
@@ -6,4 +7,5 @@
 -keep class io.flutter.**  { *; }
 -keep class io.flutter.plugins.**  { *; }
 -dontwarn io.flutter.embedding.**
+## Sqlite Encryption
 -keep class net.sqlcipher.** { *; }