Fix failing sql server tests (part 2)

modules/flowable-engine/src/main/resources/org/flowable/db/drop/flowable.mssql.drop.engine.sql

@@ -16,6 +16,7 @@ if exists (select TABLE_NAME from INFORMATION_SCHEMA.TABLES where TABLE_NAME = '
 if exists (select TABLE_NAME from INFORMATION_SCHEMA.TABLES where TABLE_NAME = 'ACT_RU_TASK') alter table ACT_RU_TASK drop constraint ACT_FK_TASK_PROCINST;
 if exists (select TABLE_NAME from INFORMATION_SCHEMA.TABLES where TABLE_NAME = 'ACT_RU_TASK') alter table ACT_RU_TASK drop constraint ACT_FK_TASK_PROCDEF;
 if exists (select TABLE_NAME from INFORMATION_SCHEMA.TABLES where TABLE_NAME = 'ACT_RU_VARIABLE') alter table ACT_RU_VARIABLE drop constraint ACT_FK_VAR_EXE;
+if exists (select TABLE_NAME from INFORMATION_SCHEMA.TABLES where TABLE_NAME = 'ACT_RU_VARIABLE') alter table ACT_RU_VARIABLE drop constraint ACT_FK_VAR_PROCINST;
 if exists (select TABLE_NAME from INFORMATION_SCHEMA.TABLES where TABLE_NAME = 'ACT_RU_JOB') alter table ACT_RU_JOB drop constraint ACT_FK_JOB_EXECUTION;
 if exists (select TABLE_NAME from INFORMATION_SCHEMA.TABLES where TABLE_NAME = 'ACT_RU_JOB') alter table ACT_RU_JOB drop constraint ACT_FK_JOB_PROCESS_INSTANCE;
 if exists (select TABLE_NAME from INFORMATION_SCHEMA.TABLES where TABLE_NAME = 'ACT_RU_JOB') alter table ACT_RU_JOB drop constraint ACT_FK_JOB_PROC_DEF;