rm unneccessary calls to Array.slice() from ember-data models.

packages/ilios-common/addon/models/ilm-session.js

@@ -35,12 +35,9 @@ export default class IlmSession extends Model {
    * @returns {Promise<Array>}
    */
   async getAllInstructors() {
-    const instructors = (await this.instructors).slice();
-    const instructorGroups = (await this.instructorGroups).slice();
+    const instructors = await this.instructors;
+    const instructorGroups = await this.instructorGroups;
     const instructorsInInstructorGroups = await Promise.all(mapBy(instructorGroups, 'users'));
-    return uniqueValues([
-      ...instructors,
-      ...instructorsInInstructorGroups.map((instructorGroup) => instructorGroup.slice()).flat(),
-    ]);
+    return uniqueValues([...instructors, ...instructorsInInstructorGroups.flat()]);
   }
 }

packages/ilios-common/addon/models/session.js

@@ -595,7 +595,7 @@ export default class SessionModel extends Model {
 
   async getTotalSumOfferingsDurationByInstructor(user) {
     const offerings = await this.offerings;
-    const offeringsWithUser = await filter(offerings.slice(), async (offering) => {
+    const offeringsWithUser = await filter(offerings, async (offering) => {
       const instructors = await offering.getAllInstructors();
       return mapBy(instructors, 'id').includes(user.id);
     });

packages/ilios-common/addon/models/term.js

@@ -110,7 +110,7 @@ export default class Term extends Model {
   }
 
   async getAllDescendants() {
-    const children = (await this.children).slice();
+    const children = await this.children;
     const childrenDescendants = await Promise.all(
       children.map((child) => child.getAllDescendants()),
     );

packages/ilios-common/addon/models/user.js

@@ -626,9 +626,7 @@ export default class User extends Model {
   async getLowestMemberGroupInALearnerGroupTree(learnerGroupTree) {
     const learnerGroups = await this.learnerGroups;
     //all the groups a user is in that are in our current learner groups tree
-    const relevantGroups = learnerGroups
-      .slice()
-      .filter((group) => learnerGroupTree.includes(group));
+    const relevantGroups = learnerGroups.filter((group) => learnerGroupTree.includes(group));
     const relevantGroupIds = mapBy(relevantGroups, 'id');
     const lowestGroup = relevantGroups.find((group) => {
       const childIds = group.hasMany('children').ids();

packages/ilios-common/addon/models/vocabulary.js

@@ -15,8 +15,7 @@ export default class Vocabulary extends Model {
   terms;
 
   async getTopLevelTerms() {
-    const terms = await this.terms;
-    return filter(terms.slice(), async (term) => {
+    return filter(this.terms, async (term) => {
       return !(await term.parent);
     });
   }